The party which has ruled Malaysia since independence in 1957 could lose power over a dispute between the current prime minister and his predecessor, Deputy Prime Minister Najib Razak said.

Najib, who is also deputy president of Umno, said the party must avoid a structural split to ensure it remains strong, the state Bernama news agency reported late Saturday.

"If the top (leaders) cause trouble, it will break the structure," Najib said.

"As long as we don't learn from history, we can repeat the mistakes. We don't want the dark history to happen again in the party."

Najib said Umno must remain united to continue as the backbone of the country's administration. It is the dominant member of the ruling Barisan Nasional coalition.

Dr M fomenting a split

Former premier Mahathir Mohamad has been accused of fomenting a split in Umno with strident attacks on his successor Prime Minister Abdullah Ahmad Badawi.

The elder statesman has denied he was causing a rift within the party or that he wants Abdullah to step down.

Najib said any rift in the party's top leadership could cause a structural split which could mean a loss of power by the majority Malays.

Mahathir has vowed to continue his attacks on a number of government policies, including the scrapping of plans for a bridge to Singapore, as well as alleged nepotism involving some of Abdullah's family members.

He also began circulating a letter to some three million Umno members alleging the party's leadership was stifling him by pressuring Umno groups to cancel speaking engagements.