An Ivory Coast rebel group has accused President Laurent Gbagbo of "playing with fire" by breaking the terms of a French-brokered ceasefire.
Rebels are suspicious of President Gbagbo
Movement for People of the Great West (Mpigo) leader Felix Doh said government forces had attacked their positions in the west of the country killing at least two rebels and 25 civilians.
He said he had reported the incidents to peacekeepers and warned that if they did not act immediately it would jeopardise the peace process.
In the main city, Abidjan, nine rebel ministers in the power sharing government failed to turn up for work.
If nothing is done, everything will unravel very rapidly
A small rebel team had arrived on Sunday to check security conditions and prepare for their arrival.
Last week in the capital, Yamoussoukro, rebel ministers sat down at a cabinet meeting for the first time despite reservations about security and who is running the key defence and interior ministries.
But rebel spokesman Antoine Beugre told Reuters news agency they would not be attending Wednesday's cabinet meeting in Abidjan.
A national unity government is a central part of attempts to end the conflict which has left the main rebel group, the MPCI, in control of the northern half of the country, and two smaller groups (Mpigo and MPJ) in control of some western areas.
Mpigo's leader, who spoke to reporters in the northern city of Korhogo where he has been consulting with the other rebel groups, said repeated attacks had begun last Wednesday when a helicopter gunship had opened fire on one of their positions.
Gbagbo's FPI: 10 seats
Former ruling PDCI: 10 seats
RDR: 7 seats
Main MPCI rebels: 7 seats
Western rebels: 2 seats
Others: 5 seats
Since then he said loyalist troops had burnt down five villages leaving countless civilians dead.
"If nothing is done everything will unravel very rapidly. We will not accept that at the same time as Mr Gbagbo is accepting our minister in government he is attacking our positions."
He accused the Ivorian Government of using Liberian towns as rear bases from which Liberian dissidents were attacking their positions.
"It's Gbagbo who is exporting our war to Liberia," he said.
A spokesman for the Ivorian army, Lieutenant Colonel N'Goran Aka, confirmed fighting in the area, but refused to say whether helicopter gunships had been used.
He said his forces had used every means they had to drive back rebel forces after they'd been attacked.
Last week, Liberia's Government denied backing the western-based Ivorian rebel groups.