KUALA LUMPUR, Jan 9 (AFP)

A Malaysian opposition leader Sunday urged the ruling party to rescind a decision to bar any challengers to Prime Minister Mahathir Mohamad and his deputy in upcoming party polls.

Lim Kit Siang, chairman of the Democratic Action Party (DAP), said the no-contest rule for the two top posts in the United Malays National Organisation (UMNO) was a "time-bomb which could destroy the political credibility and legitimacy" of Deputy Premier Abdullah Ahmad Badawi.

The move could "rob (Abdullah) of his chance to become the undisputed fifth Prime Minister of Malaysia," Lim said in a statement.

UMNO's Supreme Council on January 3 recommended that Mahathir and Abdullah be nominated unchallenged as party president and deputy president in leadership polls on May 11.

By tradition the UMNO president and deputy president are also prime minister and deputy premier. But the party deputy presidency has been vacant since Mahathir sacked Anwar Ibrahim as deputy premier in September 1998. Anwar was later expelled by UMNO's Supreme Council.

The no-contest decision further strengthened Abdullah's status as heir apparent to Mahathir, who said after winning a fifth term in November general elections that this would be his last one.But the move has drawn flak from some members who say it is undemocratic and will weaken the party.

Lim said Sunday that Abdullah "still has to make a real mark for himself" although he has been deputy premier and home minister for a year. Mahathir's refusal to appoint Abdullah as acting premier in a planned three-week absence abroad, merely allowing him to take over his duties, has not strengthened Abdullah's political position at all, Lim said.

Mahathir will take a two-week vacation from Wednesday before making a working trip to Switzerland. This will be his longest break since May 1997 when he took a two-month holiday and appointed then deputy Anwar as acting premier.

Lim urged Abdullah to show "he has political character of his own by immediately responding to widespread adverse reactions of UMNO grassroots to the no-contest rule by getting the Supreme Council to rescind it."Failure to do so would make Abdullah seen as "weak, indecisive and vacillating," he added.

Abdullah was formerly foreign minister before being named to his new posts in January last year. He is now one of three UMNO vice presidents and has been performing the deputy president's functions since Anwar's downfall. If Mahathir stays in office for a full five-year term, Abdullah could still be challenged in triennial UMNO leadership election in 2003.

UMNO dominates the National Front coalition which has ruled since independence in 1957.