The criticism was led by Mahathir Mohamad, who hand-picked Abdullah to be his successor in 2003, but who is now the prime minister's most vocal critic.
On Tuesday about 2,000 Umno members - including Mahathir and his son Mukhriz - gathered at a conference to analyse the unprecedented election losses suffered by the coalition party.
The meeting however turned into a free-for-all session after each member took the stage and began to bitterly criticise Abdullah.
"We cannot deny the truth when there is a cancer," said Mahathir, adding that Abdullah has lost touch with reality because he is surrounded by "yes men".
"I call on him to resign," said the former leader who was prime minister for 22 years before he stepped down amid calls for his resignation.
|Mahathir, left, chose Abdullah to |
succeed him in 2003 [AFP]
"Anyone else would have done so already, but he is shameless."
The open display of anger is a clear sign of a deep crisis within the ruling coalition, which is still reeling from its worst-ever election performance.
In the March 8 polls, the ruling coalition lost its long-standing two-thirds parliamentary majority to a loose opposition coalition.
Five state governments also fell to opposition control.
Echoing his father's sentiments, Mukhriz Mahathir, a senior Umno official, said: "We have reached a crossroads."
He said the election results were "not a wake up call but a slap in the face".
Mukhriz accused Abdullah of failing to control rampant corruption, nepotism and cronyism, in an apparent reference to his son-in-law, Khairy Jamaluddin, who is believed to wield enormous influence in the government.
"We have been told to keep silent ... I urge you to stand with me to seek the truth and find a resolution," he said, adding that it was vital for Umno's survival.