Turkey's prime minister, Recep Tayyip Erdogan, yesterday fiercely attacked an online apology for the alleged genocide of Armenians by Ottoman forces in the first world war, warning that it could derail efforts to restore long-severed ties with Armenia.

The apology - organised by Turkish intellectuals in the form of a petition - provoked an outcry from right-wing nationalists, and Erdogan added his voice by making clear he felt Turkey had nothing to apologise for. "I neither accept nor support this campaign. We did not commit a crime, therefore we do not need to apologise," he said. "It will not have any benefit other than stirring up trouble, disturbing our peace and undoing the steps which have been taken."

Yesterday afternoon organisers claimed more than 11,100 people had signed the apology, two days after it was launched. Signatories include prominent academics, writers and journalists. British singer Peter Gabriel has also lent support, although the petition is only intended for Turks.

One organiser, Cengiz Aktar, professor of EU studies at Istanbul's university of Bahcesehir, dismissed Erdogan's "knee-jerk" remarks and said the number of signatories showed him to be out of step. "From now, anyone who speaks about the Armenian question will have to take into account this expression of consciousness. It's a new element in the debate."

The apology does not mention the word genocide, but acknowledges that Armenians suffered a "great catastrophe" in 1915, while criticising Turkey's denial. Armenia's government, supported by historians and an influential disaspora, says up to 1.5 million Armenians died in expulsions by the Ottoman imperial government.

Turkey rejects the claims but has proposed a joint commission to investigate.