LONDON -- British Prime Minister Keir Starmer held a phone conversation with US President Donald Trump on Sunday evening to advance what Downing Street described as "productive negotiations" towards an "economic prosperity deal".

According to a statement, both leaders have agreed to continue negotiations this week. Starmer also updated Trump on last week's meeting of the "coalition of willing" in Paris, and they agreed to keep up the pressure on Russia.

Trump has designated April 2 as "Liberation Day", when he plans to announce a set of tariffs affecting all US trade partners. Although the details of the expected tariffs remain unclear, anxiety is growing among the US allies.

Britain is expected to face added challenges to gear up its economic growth once the tariffs come into force.