Hamas has accused senior aides of the Palestinian President, Mahmoud Abbas, of spying for Israel, underscoring an intensification of Palestinian infighting even in the face of Israel's bombardments in the Gaza Strip.

The charges are part of a wider Hamas media campaign depicting Fatah leaders as colluding with the Israeli military onslaught that has taken the lives of 390 Palestinians in Gaza. This includes allegations that the former Fatah strongman in Gaza, Mohammed Dahlan, whose forces were defeated by Hamas in its June 2007 takeover of the Strip, met Israeli intelligence officials several weeks ago to discuss Israeli plans for a strike in Gaza. Mr Dahlan, according to an account on the Islamist movement's website, urged Israel to deal a "painful blow" to Hamas.

The charge of spying was made by a Hamas spokesman, Fawzi Barhoum, also on the movement's website and in remarks broadcast on al-Jazeera, the satellite television station based in Qatar. They were angrily denied by Fatah leaders.

Mr Barhoum alleged that Fatah had formed a cell with the purpose of "contacting various Fatah followers in Gaza to collect information on secret Hamas locations and on the whereabouts of the leadership" that is hiding from the Israeli military. The cell was under the leadership of a senior Abbas adviser, Tayeb Abdul-Rahim, and information gathered would be passed on "through the channels of security co-operation with the enemy," Mr Barhoum added.

Palestinians say that allegations of collusion are believed by much of the public. "The reports are not necessarily right, but people believe the reports, not the authority," said Hani al-Masri, a columnist for the al-Ayyam newspaper which takes a pro-Abbas line. "After all, it is known that the authority does have security co-ordination with Israel."

The Hamas allegations came after the movement rebuffed an invitation by Mr Abbas to discuss Gaza. Abdallah Abdallah, a pro-Abbas member of the Palestinian Legislative Council, said the Hamas allegations were "baseless".