Palestinian gunmen in the West Bank have broken up a meeting of Yasser Arafat's Fatah movement called to discuss Palestinian Authority reform.
Palestinian factions are jostling for political influence
Some 20 men loyal to Mr Arafat fired into the air outside the meeting of a rival faction in Nablus, reports said.
The meeting was being attended by Fatah members of the Palestinian parliament and senior officials from the movement.
There were no reports of casualties and calm was restored after the meeting was called off.
It seems the gunmen who succeeded in disrupting the meeting were Arafat loyalists, suspicious that a conspiracy was being hatched against their veteran leader.
It is a measure of just how high tensions are running within Fatah, the main faction that controls the Palestinian Authority.
The battle is couched in terms of fighting corruption and cronyism - of reforming the Authority to make it more democratic and accountable.
But at its heart is a power struggle that has been brought to a head by the prospect of an Israeli withdrawal from the Gaza Strip.
The meeting is believed to have been broken up by Arafat loyalists
Israel says it will not negotiate a handover to the Palestinians, but it makes little secret of its preference for Mr Arafat's main rival, his former security chief in Gaza, Mohammed Dahlan.
Mr Dahlan is young, dynamic and a fluent Hebrew speaker. He has in the past shown himself willing to confront militant groups such as Hamas and Islamic Jihad.
Mr Dahlan has built up an impressive power base in Gaza, where his criticisms of the Fatah old guard find a receptive audience.
Many see his hidden hand in the wave of Palestinian protests against Mr Arafat's power structure in both Gaza and the West Bank.
On Sunday, a Kuwaiti newspaper published Mr Dahlan's most direct attack to date on Mr Arafat, accusing him of sitting on Palestinian corpses when what his people needed was support and a new mentality.