The EU has outlined its strategy for Brexit negotiations, suggesting talks on a trade deal could begin once “sufficient progress” is made on a separation settlement with the UK.

The draft guidelines, issued by European Council President Donald Tusk, argue for a “phased approach” in talks.

The draft will be sent to the 27 member states for approval. It will set the tone for two years of negotiations.

The UK formally triggered the Brexit process on Wednesday.

It had called for simultaneous talks on exit terms and future trade ties.

• Key points from the EU’s response
• EU wants ‘divorce bill’ settled first
• Brexit: What happens now?
• Issues in Brexit talks
• UK’s letter triggering Article 50: Main points

In a news conference in Malta on Friday, Mr Tusk said: “Starting parallel talks on all issues at the same time as suggested by some in the UK will not happen.”

“Only once we have achieved sufficient progress on the withdrawal can we discuss the framework for our future relationship,” he added.

Talks would be “difficult, complex and sometimes even confrontational”, he predicted, but the EU would not “pursue a punitive approach”.

UK Prime Minister Theresa May formally triggered the Brexit process by sending the Article 50 notification letter to Mr Tusk on Wednesday.

The two are to meet in London ahead of an EU summit on Brexit, which will not include her, on 29 April.

Sign-up to get news from the BBC in your inbox, each weekday morning

What do the guidelines say?

The draft says the EU’s overall objective is “to preserve its interests, those of its member states, its citizens and its businesses”.

Calling for a “phased approach giving priority to an orderly withdrawal”, it suggests starting with discussions on the separation arrangement. They could then move on to talks about a future trade relationship between the EU and the UK.

The draft raises the issue of the UK financial bills with the EU, estimated to be as much as €60bn (£51bn; $64bn).

In a sign of the bloc’s determination to secure a “divorce bill”, it says that a “single financial settlement should ensure that the Union and the United Kingdom both respect the obligations undertaken before the date of withdrawal”.

The document also calls for “flexible and imaginative solutions” for the issue of the UK’s land border with the Republic of Ireland, with the aim of “avoiding a hard border”.

What about future ties on security?

Mr Tusk told reporters: “Strong ties reaching beyond the economy, and including security co-operation remain in our common interest.”

He added: “Our partners are wise and decent partners and this is why I’m absolutely sure that no-one is interested in using security co-operation as a bargaining chip.”

Mrs May’s letter had been interpreted by some as threatening to withdraw co-operation with the EU on security matters.

What next? Analysis by BBC Europe editor Katya Adler

This is the start of a two-year, cross-Channel political roller-coaster ride. The EU’s draft guidelines for Brexit are uncompromising and firm.

They say they will update them “as necessary” during negotiations, meaning they are ready for anything, including, the text explicitly says, for talks with the UK to fail altogether.

Gone are the words of sadness and regret at Britain’s departure. The message is: Roll up your sleeves, we’re ready for you.

How have British politicians reacted?

Foreign Secretary Boris Johnson said: “There’s a lot of goodwill… to achieve what the prime minister has said she wants to achieve, which is an orderly transition.”

But Liberal Democrat leader Tim Farron, who had campaigned against Brexit, said the guidelines showed “the strength of the EU in these negotiations and the carelessness of the UK government in isolating themselves from our European allies”.

Labour MP Owen Smith said: “Two days into a two-year negotiation and the government’s lofty rhetoric is colliding with hard reality. The prime minister’s plan for Britain is a pipe dream.”

Ukip leader Paul Nuttall said that the EU’s wish to “play hardball with the reciprocal rights of individual citizens” was not in the interest of member states, and that as Brexit neared they would see the EU’s “rigid approach”, not the UK, as the main problem.