A Japanese popstar has apologised after speaking out about allegedly being assaulted in her own home by two male 'fans'.

Maho Yamaguchi, 23, revealed this week that she had been 'attacked by two men' at her flat in Niigata, central Japan, accusing fellow members of the pop-group NGT48 of leaking her personal details to fans.

Yesterday, Yamaguchi apologised during a performance in the city, bowing deeply to the crowd before saying she regretted 'causing trouble' by speaking publicly about the alleged assault.

Apology: Maho Yamaguchi bows on stage in Niigata, Japan, as she apologises to her fans for speaking out about an alleged assault which took place in December

NGT48 is a so-called 'idol group', a Japanese manufactured performance group with 48 members, of which Yamaguchi is a 'team leader'.

Local media reports that Yamaguchi was attacked on December 8, as she entered her flat in Niigata, by two men 'grabbing her by the face'.

The 23-year-old 'screamed in fear' which saw the two men cover her mouth to silence her, Kotaku.com reports.

The men, two 25-year-old students, were arrested for assault, but later released without charges.

Police said that the suspects 'only wanted to talk to Yamaguchi, and didn't think it would be a big deal', according to AnimeNewsNetwork.

Yamaguchi, 23, revealed this week that she had been 'attacked by two men' at her flat, accusing fellow members of the pop-group NGT48 of leaking her details to fans

Girl group: Maho Yamaguchi, 23, is one of 48 members of NGT48, pictured onstage during the 2015 Asia Song Festival in Busan, South Korea

Despite the alleged assault taking place last month, Yamaguchi did not address the incident until earlier this week.

In an emotional video livestreamed on social media, Yamaguchi broke down in tears as she spoke for the first time about the attack.

She claimed that someone in NGT48 had leaked her personal details, including her address, and that this had seen the two men turn up at her door.

With tears streaming down her face, she relayed her fear as she was pinned down by the two attackers outside her flat. She claimed she was able to escape when they became distracted by the building's lift.

She said she reported the incident to her management, and that she had decided to speak up when nothing came of her complaints.

Japan's Prime Minister Shinzo Abe poses with NGT48 members in Shinjuku Gyoen park in Tokyo in spring 2016

A translation posted on Twitter quotes her as saying 'I wanted to speak out sooner but [management] said they would take care of everything, so I waited this whole month while in fear.

'However, there were no results. The people who did the evil deed are all just as they were.'

The day after the livestream, Yamaguchi took to the stage to apologise to her fans 'for causing trouble' during a performance.

Taking a deep bow in front of a crowd, she said she was sorry for 'causing troubles for those who have taken care of me'.

NGT48 management denied that another member of the group leaked her address to the attackers.