Lutz Bachmann has been reinstated as the head of Germany’s anti-Islamisation movement Pegida, a month after resigning over a photo showing him posing with a Hitler moustache.

The group confirmed on its Facebook page that the 42-year-old had been re-elected as chairman on Sunday by the six other members of the organisation’s leadership committee.

The Sächsische Zeitung reported last week that the Hitler moustache on the now infamous photo had been added after the photo was taken – though Bachmann did not mention this when the photo went viral.

“No one would have believed me at that moment,” he told the Guardian on Monday. “All the media in the world reported it. On the original photo, I did not have a moustache. Since then, it has been revealed as a forgery, but in that moment, it simply wasn’t possible to refute it, and in order to avoid damage I stepped down – but only as chairman. I never left the organisation.”

Bachmann also stressed that he should not be considered a leader of the group. “There is a club, there are seven members, and each person has the same power,” he said. “The board chairman post is just because German law requires a board chairman on paper for any club. There is no leader.”

The picture of Bachmann went viral after it was published by a local newspaper, the Dresden Morgenpost. A Morgenpost reader discovered the photograph, along with what appeared to be a closed Facebook conversation between Bachmann and one of his Facebook contacts, in which he described immigrants as cattle, scumbags and trash.

Pegida has been holding weekly demonstrations in Dresden since last October against what it perceives as the Islamisation of Europe. The protests have attracted international media attention and crowds of 17,000 at one point, and associated rallies have taken place in other German cities, but the leadership has been dogged by infighting. The controversy over the Hitler photo and Bachmann’s Facebook comments was seen as particularly damaging.

Bachmann’s resignation in January was followed by an exodus of leading members, apparently in an attempt to distance themselves from openly racist supporters. The most prominent departure was that of Kathrin Oertel, who split from the group to found a new rightwing organisation called Direkte Demokratie für Europa, or Direct Democracy for Europe.

Bachmann, who carries convictions for drug possession, assault and burglary, has continued to speak at Pegida demos in Dresden. At last week’s event he imitated the 16th century church reformer Martin Luther and nailed 10 “theses” to the door of Dresden’s Kreuzkirche church. These widened the group’s anti-immigration message to a number of issues, including opposition to a proposed EU-US trade agreement.

In the same Facebook post announcing Bachmann’s reinstatement, Pegida also welcomed its latest member - Tatjana Festerling, a former member of the eurosceptic Alternative for Germany party who attracted criticism last year for praising the Hooligans Against Salafists demo in Cologne. Bachmann said Festerling would almost certainly be the group’s new spokeswoman.

Pegida has attracted close to 160,000 likes on its Facebook page, which remains its only official web presence, but numbers at recent demos in Dresden have dwindled from a highpoint of 17,000 in January to around 2,000 in the last two weeks.