Media playback is unsupported on your device Media caption ‘Brexit will be painful for Britain’ – Irish Foreign Minister Charlie Flanagan

Voting to leave the European Union was a "bad decision" for the UK, the Irish foreign minister has said.

Charlie Flanagan said Brexit could be "painful" for the UK and his country, which he added should not be "placed in a position of more disadvantage".

He also urged negotiators to keep the Common Travel Area between Northern Ireland and the Republic.

The comments come after Prime Minister Theresa May met European Council President Donald Tusk in London.

Mr Flanagan told BBC's Newsnight it was "absolutely essential" there was no return to a hard border on the island of Ireland - which is expected to be a key element of Brexit negotiations between the UK and EU.

"The Good Friday Agreement remains the foundation stone of our peace, and anything adverse to that agreement will not be acceptable," he said.

However, despite his criticism of the decision to leave, the Irish minister said he believed there was no intent to punish Britain among EU members, adding that the relationship between the UK and the Republic of Ireland was its "warmest ever".

He said: "I believe [Brexit] was a bad decision, but of course as a democrat I fully respect and recognise the will and wishes of the British people. We've got to deal with that now.

"The Article 50 process has commenced, and I believe it's essential now that we get through the negotiations in such a way that the end result can be as close as possible a relationship between the European Union and the United Kingdom, albeit with the UK gone."

'Good and friendly' talks

On Friday, Mrs May and Mr Tusk met at 10 Downing Street for the first time since Article 50 was triggered, with Gibraltar at the heart of the talks.

In its draft negotiating guidelines, published last week, the EU said decisions affecting Gibraltar - a UK overseas territory - would have to be taken with the agreement of the Spanish government.

This led to former Conservative leader Lord Howard saying the prime minister would defend Gibraltar in the same way Margaret Thatcher defended the Falkland Islands.

Image copyright EPA Image caption The talks between Mrs May and Mr Tusk lasted two hours.

Mrs May laughed off the prospect of war with Spain, but after her meeting with Mr Tusk, a Number 10 spokesman said she had been clear she was determined to achieve the "best possible deal" for Gibraltar as well as the UK.

"The PM also made clear that... there would be no negotiation on the sovereignty of Gibraltar without the consent of its people," he added.

EU sources told the Press Association it had been a "good and friendly" meeting.

One source added: "They agreed to stay in regular contact throughout the Brexit process to keep a constructive approach and seek to lower tensions that may arise, also when talks on some issues like Gibraltar inevitably will become difficult."