(Corrects first name of Nissan CEO to Hiroto, not Hirohito, paragraph 3)

TOKYO, Aug 31 (Reuters) - Britain and Japan are aiming to put in place a bilateral trade agreement "pretty much immediately" after Brexit, a government source said on Thursday as Prime Minister Theresa May tries to reassure businesses and politicians during a visit to Tokyo.

"Our intention would be for our deal to come into force pretty much immediately," a government source said on Thursday. "That's the UK position and they've (Japan) agreed to it."

The source also said that May had met Toyota Chairman Takeshi Uchiyamada, Nissan CEO Hiroto Saikawa and Hitachi Chairman Hiroaki Nakanishi during her trip.

The meetings were "enthusiastic and positive", the source said. (Reporting by William James in Tokyo; writing by Costas Pitas in London; editing by Kate Holton)