KUALA LUMPUR - A battle for senior leadership posts in Malaysia's ruling party was hit with a bombshell Tuesday as 15 members including several top figures were found guilty in an anti-corruption probe.

Mohamad Ali Rustam, a leading contender for the party's deputy presidency, which comes up for grabs in internal elections later this month, was the most prominent of those implicated.

If successful he would have become deputy prime minister and by the party's convention next in line for the prime ministership after Najib Razak, the current deputy, becomes premier later this month.

The party's disciplinary chief, Ahmad Rithauddeen Ismail, said Mohamad Ali was disqualified from running for the post after three of his aides were found guilty of vote-buying.

"It is presumption of guilt, as the principle is that he is liable for the wrongdoing of his agents," the disciplinary head told a press conference.

The United Malays National Organisation (UMNO), which heads the coalition that has governed Malaysia for half a century, is in turmoil as it faces sweeping leadership changes at its March 24-28 conference.

Prime Minister Abdullah Ahmad Badawi is to stand aside for his deputy Najib, creating the key vacancy, but there has also been frenzied campaigning for other senior positions that have become available.

Khairy Jamaluddin, Abdullah's son-in-law and an ambitious but controversial political figure in his own right, was also found guilty of having agents who were involved in vote-buying and given a warning.

He will however be allowed to run for the influential post of UMNO youth chief.

The other 13 figures named, who were all found guilty of involvement in "money politics" during intense campaigning for the leadership spots, were given suspensions and warnings.