Japan's government has admitted an official photo of its new cabinet was manipulated to make members look less unkempt after online speculation that it had been edited.

Photos taken by local media showed the new prime minister, Shigeru Ishiba, and his defence minister with small patches of white shirt showing under their suits.

But in the official photo issued by the prime minister's office on Thursday, the untidiness had disappeared.

After plenty of online mockery, a government spokesperson on Monday said "minor editing was made" to the image.

Spokesman Yoshimasa Hayashi told reporters the image had been manipulated as group photos taken by the prime minister's office "will be preserved forever as memorabilia".

He added that "minor editing is customarily performed on these photos".

His comments come after a barrage of mockery on social media.

"This is more hideous than a group picture of some kind of a seniors' club during a trip to a hot spring. It's utterly embarrassing," one user wrote on X.

Another user said it was clear the cabinet members were wearing suits in the incorrect size.

Other users have been referring to the cabinet - and their trousers - as "ill-fitting", according to local media.

The photograph was taken on Thursday following the first meeting of Japan's new cabinet.

A few days earlier, Ishiba, 67, replaced outgoing prime minister, Fumio Kishida, as chief of the country's ruling party.

He was officially appointed to the role of prime minister on Tuesday.

Ishiba has already announced plans for a snap election on 27 October.

"It is important for the new administration to be judged by the people as soon as possible," he told a news conference in Tokyo, according to Reuters.

The election, which is set to take place more than a year before it is due, will decide which party controls parliament's lower house.