Turkey and the United Kingdom plan to sign a free trade deal once Britain leaves the European Union, Turkish Prime Minister Binali Yildirim said on Saturday.

Yildirim made the comment in a joint news conference with U.K. Prime Minister Theresa May, who was visiting Ankara after a trip to Washington for President Donald Trump's first meeting with a foreign leader.

In both visits, she has tried to drum up trade deals for Britain, attempting to strengthen her hand in negotiations to leave the bloc.

During May's visit to Ankara, Turkey and Britain signed a deal to jointly build fighter jets. Britain's BAE Systems and Turkish Aerospace industries signed the 100 million-pound (nearly $125.5 million US) agreement establishing a partnership for the development of Turkey's fighter jet program.

British Prime Minister Theresa May was greeted by Turkish President Recep Tayyip Erdogan at the presidential palace in Ankara before holding talks with Turkey's prime minister. Turkey joins 13 other countries in trade talks with the U.K. (Andrew Parsons/Getty)

Yildirim also said the two countries had agreed to strengthen cooperation in the fight against terrorism.

"The relationship between Turkey and the United Kingdom has always been important, but it is arguably even more vital today, for Turkey sits on the frontline of some of the most difficult and serious challenges we face," May told a media briefing after the meeting.

"This relationship is central to our capacity to tackle the terrorist threat to the U.K. Turkey already does a huge amount to disrupt the threat posed to our countries by terrorists, including foreign fighters leaving Syria. And today we've agreed to strengthen our cooperation on security through a new strategic security partnership.

"This will help our two governments and security services to work even more closely together in important areas such as intelligence sharing, aviation security and domestic security.This partnership will help Turkey as it grapples with the threat posed by heightened terrorist attacks in this country," she said.

Regional issues cannot be solved by closing the doors on people. We expect the Western world to lighten Turkey's burden. - Turkish Prime Minister Binali Yildirim

Trump's sweeping ban on people seeking refuge in the United States is no solution to problems, Yildirim said on Saturday, adding that Western countries should do more to help ease Turkey's refugee burden.

The new Republican president on Friday put a four-month hold on allowing refugees into the United States and temporarily barred travellers from Syria and six other Muslim-majority countries, although NATO ally Turkey was not among them.

Trump and May discussed security, trade and their commitment to NATO during a briefing at the White House on Friday. (Pablo Martinez Monsivais/Associated Press)

When asked by a reporter about Trump's ban during a joint news conference with May in Ankara, Yildirim said: "Regional issues cannot be solved by closing the doors on people. We expect the Western world to

lighten Turkey's burden."

"You can build a wall but it's not a solution. That wall will come down like the Berlin wall," he said, adding Turkey has spent some $26 billion on sheltering refugees.

Washington is responsible for its policy on refugees, May said at the joint news conference when asked about Trump's ban on people from seven Muslim-majority countries seeking refuge in the United States.

On Sunday, her official spokesman said that May does "not agree" with Trump's order and will challenge the U.S. government if it has an adverse effect on British nationals.