Boris Johnson has thanked Japanese prime minister Shinzo Abe for his service and wished him good health following his abrupt resignation.

Mr Abe announced he is stepping down for health reasons after suffering for many years from ulcerative colitis, an inflammatory bowel disease.

Mr Abe said he did not want his illness, which has worsened recently, to get in the way of decision-making, and apologised to the Japanese people for not completing his term in office.

In a tweet, the UK Prime Minister said: “Shinzo Abe has achieved great things as PM of Japan – for his country and the world.

“Under his stewardship the UK-Japan relationship has gone from strength to strength in trade, defence and our cultural links.

“Thank you for all your years of service and I wish you good health.”

Foreign Secretary Dominic Raab said: “I was sorry to learn that Shinzo Abe is stepping down as Prime Minister, and I pay tribute to the great things he has achieved as Japan’s longest-serving leader.

“He leaves a strengthened UK-Japanese friendship, which we look forward to continuing in the years ahead. I wish him well for the future.”

Mr Abe, who became Japan’s longest-serving prime minister last year, said his health started to decline as his condition made a resurgence in July.

He said he is receiving treatment on a regular basis which would make it hard for him to carry out his prime ministerial duties, and came to the conclusion that he should step down.

Mr Abe’s current period in office began in 2012.

In 2017, he resigned unexpectedly from an earlier term as prime minister because of his illness, a chronic condition he has lived with since his teenage years.