The leaders of the two rebel factions in Liberia issued a joint statement on Monday calling for the immediate replacement of Gyude Bryant as the head of Liberia's three-month-old transitional government. They did not say who should replace him.
The statement was signed by Sekou Damate Conneh, leader of the main rebel group, Liberians United for Reconciliation and Democracy (LURD), and Thomas Nimely-Yaya, chairman of the Movement for Democracy in Liberia (MODEL).
They accused Bryant, a respected businessman, of being biassed, inadequate and inept. The also complained that LURD and MODEL fighters were being left out of a new police force being trained by UN peacekeepers.
One of Bryant's aides said the rebel demands for the replacement of Bryant, whom they helped choose at a peace conference last August, was "a sad moment in Liberia's transition from war to peace."
"Those warlords just want to seek their own interest," he added.
US Ambassador to Liberia, John Blaney, a key figure in talks that led to the departure of former president Charles Taylor and a ceasefire between the warring parties, immediately came to Bryant's defence.
"The US government has seen nothing done by Mr. Bryant that will justify such a request and we think that the transitional government - in its first hundred days - has made progress," Blaney told reporters.
"Let me just remind all sides, that any attempt to destabilize Liberia, including the NTGL [National Transitional Government of Liberia] will not be tolerated", he warned.
The US government has refrained from sending troops to join the UN peacekeeping force in Liberia, but it has earmarked several hundred million dollars to fund the disarmament process and the reconstruction of the country's battered infrastructure.
Gossips on the streets of Monrovia interpreted the rebel challenge to Bryant as a bid to scupper the United Nations' delayed programme to disarm an estimated 40,000 former combatants in Liberia.
The disarmament programme was put on ice after a difficult start in December and is due to resume at an unspecified date in February.
Despite falling out frequently with the three armed factions in Liberia, Bryant remains popular among ordinary Liberians, weary of 14 years of near constant civil war.
His previous rows with LURD, MODEL and the remnants of Taylor's government and army were mostly about jobs in government.
Conneh, who is currently facing a challenge by his estraged wife Aisha Keita for the leadership of LURD, has opted to remain outside Bryant's broad-based coalition government.
However, Nimely serves as Foreign Minister in the administration, which is due to run Liberian until fresh elections in October 2005.
Bryant was chosen by consensus as head of the transitional government by all the delegates to the Liberian peace conference. He was sworn in on 14 October.