President Ashraf Ghani of Afghanistan has condemned a massive bomb attack in the capital Kabul, which killed at least 90 people, as “cowardly”.

A suicide attacker detonated a bomb hidden inside a tanker truck close to the heavily protected diplomatic area during the morning rush hour.

Some 400 people were injured by the blast, which left a deep crater.

No group has said it carried out the attack but Taliban militants denied being involved.

Recent bomb attacks in Kabul have been claimed either by the Taliban or so-called Islamic State (IS).

Most of the casualties were Afghans but foreign nationals were also injured, including 11 US citizens. The bomb exploded close to the German embassy, where a number of staff were injured.

Authorities in Germany postponed a deportation flight due to return failed Afghan asylum seekers, with a government source telling AFP news agency that diplomatic and consular staff had “more important things to do than to deal with organisational matters” so soon after the attack.

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When and where did the attack take place?

The bomb went off at about 08:20 local time (03:50 GMT) near Zanbaq Square, outside the Green Zone, Capt William Salvin, spokesman for Nato’s Resolute Support Mission, told the BBC.

Reports vary as to the kind of vehicle used to deliver the bomb – either a water or sewage tanker.

One Western diplomatic source told AFP news agency the blast had been caused by more than 1,500kg (3,307lb) of explosives.

The area is home to key buildings including embassies and the presidential palace.

More than 50 other vehicles were destroyed.

Who were the casualties?

Many of the casualties appear to have been Afghan civilians on their way to work or school and office workers in nearby buildings.

“I have never seen such a terrible explosion in my life,” local shop owner Sayed Rahman told Reuters news agency after his store was badly damaged.

Another resident, Abdul Wahid, told the BBC the blast had been “like a heavy earthquake”.

Several international and local sources have been reporting on casualties:

• Mohammed Nazir, who had worked as a driver for BBC Afghan for more than four years, died in the blast, the BBC confirmed, adding that four of his colleagues were injured
• 11 US citizens working as contractors at the American embassy were injured
• German Foreign Minister Sigmar Gabriel said employees at the German embassy had been injured and one Afghan security guard had died
• French officials said the country’s embassy had been damaged but no French casualties reported
• The British embassy said all its staff were accounted for
• Two Japanese embassy staff members were slightly wounded
• Turkey said its embassy was damaged but no-one was hurt
• Afghanistan’s Tolo news agency tweeted that one of its staff members, Aziz Navin, had died
• A Tolo journalist also said some of the victims were from the Roshan mobile phone company, but this has not been confirmed

Mohammed Nazir

The BBC has been reacting to the death of its Kabul driver:

• Francesca Unsworth, BBC World Service director: It is with great sadness that the BBC can confirm the death of BBC Afghan driver Mohammed Nazir following the vehicle bomb in Kabul earlier today, as he was driving journalist colleagues to the office. Mohammed Nazir worked as a driver for the BBC Afghan service for more than four years and was a popular colleague. He was in his late 30s and he leaves a young family. This is a devastating loss to the BBC and to Mohammed Nazir’s friends and family.

• Tony Hall, BBC director-general: Many of our staff face dangerous situations every day as they report from volatile areas around the world. It’s testament to their bravery that we are able to provide trusted, impartial coverage – but consequences like this are devastating for us all. Our thoughts and prayers are with Mohammed’s family and many friends at such a very sad time.

• Waheed Massoud, BBC Afghan service: Mohammed Nazir was young. He was the father of four children and the only breadwinner in his family. He had a gentle smile and a warm personality. I knew Nazir for years and I worked with him most days of the week. BBC journalists, support staff and visitors remember him as an honest and reliable person. Most colleagues deploying from Kabul to dangerous provinces would prefer to go with Nazir.

Read Waheed’s tribute in full.

Has Germany stopped deportations indefinitely?

It appears not. AFP’s source at the interior ministry said there would be no flights for a few days – but they would resume.

Germany argues Afghanistan is a safe country for failed asylum seekers to return to – unlike Syria, for example.

Chancellor Angela Merkel condemned Wednesday’s bombing, saying “terrorism has no borders”.

“It targets us all – whether it’s in Manchester, or Berlin, Paris, Istanbul, St Petersburg or, today, in Kabul,” she said.

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In other reaction:

• UN Secretary General Antonio Guterres “expressed his abhorrence at this act and underlined the need to reinforce the fight against terrorism and violent extremism”, a spokesman said

• Hugo Llorens, special chargé d’affaires at the US embassy in Kabul, said the attack was “horrific and shameful”
• Indian Prime Minister Narendra Modi tweeted his condemnation, saying: “Our thoughts are with the families of the deceased & prayers with the injured.”

• A Pakistani Foreign Office statement denounced the attack, saying: “Pakistan, being a victim of terrorism, understands the pain and agony that such incidents inflict upon people and society.”

Who could have been behind the attack?

IS said it was behind a suicide bomb attack this month on a Nato convoy that was passing the US embassy in Kabul. At least eight civilians were killed.

It has made no comment so far on the latest attack.

When announcing the start of their major spring offensive last month, the Taliban said their main focus would be foreign forces, targeting them with a mix of conventional, guerrilla, insider and suicide attacks.

The US has about 8,400 troops in Afghanistan, with another 5,000 from Nato allies.

The Pentagon has reportedly pressed President Donald Trump to send thousands more troops back to the country to try to counter gains by the Taliban. More than a third of the country is now said to be outside Afghan government control.

A Taliban attack on an Afghan army training compound in the northern city of Mazar-e Sharif last month killed at least 135 soldiers, and led to the resignation of the defence minister and army chief of staff.

Major recent Kabul attacks

• 8 March 2017 – About 50 people killed after attackers dressed as doctors stormed Sardar Daud Khan military hospital
• 21 Nov 2016 – At least 27 dead in a suicide bomb attack on Baqir ul Olum mosque during a Shia ceremony
• 23 July 2016 – At least 80 people killed in twin bomb blasts targeting a rally by the Shia Hazara minority in Deh Mazang square
• 19 Apr 2016 – At least 28 dead in a huge explosion close to the Afghan defence ministry building
• 1 Feb 2016 – 20 killed in a suicide bomb attack at police headquarters
• 7 Aug 2015 – At least 35 people dead in separate bomb attacks across the capital

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