Egypt's pro-government Tagarod ('Impartiality') campaign will hold a sit-in outside the Presidential Palace in Cairo on 28 June – only two days before planned anti-government rallies in the same location – campaign organisers announced Tuesday.

The 'Impartiality' initiative was launched by Islamist parties and groups in response to Egypt's Tamarod ('Rebel') campaign, which aims to collect 15 million citizens' signatures in support of a withdrawal of confidence from President Mohamed Morsi.

'Rebel' campaigners are calling for mass anti-Morsi demonstrations on 30 June to demand the president's ouster and snap presidential elections. Last week, 'Rebel' spokesmen announced that they had collected over seven million signatures in support of their demands.

'Impartiality' spokesman Khaled El-Mashad told Egypt's CBC satellite television channel on Tuesday that the campaign's planned sit-in may extend to Cairo's iconic Tahrir Square and Giza's Al-Nahda Square.

El-Mashad also said the campaign had collected ten million citizens' signatures in support of President Morsi – elected last year in Egypt's first post-Mubarak presidential polls – and hoped to collect another ten million.

He went on to assert the existence of a "conspiracy" aimed at sowing violence during the upcoming demonstrations.

El-Mashad warned that "hired thugs" posing as members of Gaza's Islamist Hamas movement would be dispatched to kill anti-Morsi protesters with the aim of turning public opinion against the president and the Muslim Brotherhood group from which he hails.

On Monday, prominent Islamist politician Assem Abdel-Maged, a leading member of the ultra-conservative Al-Jamaa Al-Islamiya group and a founder of the 'Impartiality' campaign, made similar claims.

Abdel-Maged claimed to have information that 'Rebel' campaigners were planning to kill their own protesters in order to turn public opinion against Morsi and the Brotherhood.

Many Egyptians believe that Hamas, an ideological offshoot of Egypt's Muslim Brotherhood, was involved in the killing of anti-regime protesters and a spate of prison breaks during Egypt's 2011 uprising. During the Mubarak era, Hamas was frequently vilified by the state media.

'Rebel' campaigners, however, insist they will only use peaceful means to achieve their stated demands. They say their main reason for calling for early elections is that Morsi's policies are the same as those of ousted president Hosni Mubarak.

Many Islamist parties and groups allied to the Brotherhood have condemned the planned 30 June protests. A spokesman for Al-Jamaa Al-Islamiya's Building and Development Party on Tuesday attributed the planned anti-Morsi rallies to "enemies of the Islamist project" who were seeking to sow chaos in Egypt.

'Sectarian war'

Leading Brotherhood member Mohamed El-Beltagi on Tuesday warned that a "sectarian war" could erupt if the planned 30 June protests turned violent.

Speaking via Facebook, El-Beltagi asserted: "The real revolution will end [if violence breaks out], relieving the former regime of the consequences of the revolution...it will be the death knell of the revolution and the triumph of the counter-revolution."

The 'Rebel' initiative went viral shortly after its inception in May, with campaigners hitting the streets in public areas nationwide to distribute anti-Morsi petitions.

Campaign founders hope to stage a mass sit-in on the last day of June – corresponding with the end of Morsi's first year in office – that would force the president to step down, thus necessitating fresh presidential elections.