Prime Minister Theresa May will meet Turkish President Tayyip Erdogan on Saturday to discuss trade and security, her spokeswoman said, part of a charm offensive to bolster her hand in negotiations to leave the EU.

A day after meeting U.S. President Donald Trump when she won his approval and some assurances on economic cooperation, May heads to Ankara to launch a joint working group to prepare the ground for a new trade relationship after Brexit.

Her spokeswoman said May and Erdogan would discuss two key themes: "(They) will be discussing a new trade relationship following the UKs exit from the EU", and "they are expected to agree to ... a strategic security partnership."

Mays government is keen to start laying the groundwork for bilateral trade agreements for when Britain leaves the European Union - a process that will take at least two years after triggering the formal divorce talks by the end of March.

Mays spokeswoman said Turkey would be the 13th country to set up a working group on trade with Britain.

British Foreign Secretary Boris Johnson said on a visit to Ankara last year that he hoped for a "jumbo" free trade deal with Turkey after Brexit. While Ankara is not a member of the European Union, it aspires to join the bloc and has a customs union with it.

The United Kingdom was the second-largest destination for Turkish exports in 2015, buying $10.6 billion in goods, according to IMF trade data. Only Germany imports more from Turkey.

Asked whether May would raise human rights concerns since last Julys failed coup, the spokeswoman said Britain had "expressed our strong support for Turkeys democracy and institutions following the coup."

"But we have also been clear that we urge Turkey to ensure that their response is proportionate, justified and in line with international human rights obligations."

Since the failed coup, Turkey has jailed about 40,000 people pending trial and has suspended or dismissed more than 100,000 from the military, judiciary and public services.