LONDON--Prime Minister Theresa May sought to reassure Japan on Monday that Britain would remain welcoming to Japanese companies after Brexit, in a phone call between the two leaders.

"The prime minister updated Prime Minister Abe on her meeting with senior Japanese business leaders at Downing Street earlier this month and reaffirmed the government's commitment to ensuring the U.K. remains welcoming to Japanese companies," a spokesman for her office said.

Japan warned May earlier this month that its companies would have to leave Britain if trade barriers after Brexit made them unprofitable, following a meeting at Downing Street.