KUALA LUMPUR - MALAYSIA'S opposition Friday demanded a probe into the mysterious death of a political aide, who apparently plunged from the 14th floor of anti-corruption offices where he was being questioned.

Opposition figures expressed disbelief over the death of Teo Beng Hock, 30, an assistant to a member of the state cabinet in Selangor, which is ruled by the Pakatan Rakyat opposition alliance.

His body was found on Thursday sprawled on the roof of an adjacent building, after he had undergone questioning late into the night at the offices of the Malaysian Anti-Corruption Commission (MACC).

Opposition leader Anwar Ibrahim called for a high-level independent probe into the incident, which he said was part of a pattern of government harassment.

An opposition spokesman said that seven people including several legislators were arrested at the protest, and that scuffles broke out when riot police moved in to disperse the crowd.

MACC deputy commissioner Abu Kassim Mohamad said Teoh was never a suspect in the investigations into alleged misappropriation of state funds, and that he was 'a very cooperative, friendly, good and helpful witness'.

'He was never interrogated as he was not a suspect and he never showed signs of being under pressure,' he said, according to the New Straits Times.

The anti-corruption body said that Teoh, who had been due to register his marriage on Friday, had undergone questioning until 3.45am on Thursday and then chose to rest in the building after he was discharged.

It said he was seen at 6.00am sleeping on a sofa and was not seen again until his crumpled body was discovered at 1.30pm.

Malaysia's leading human rights body Suaram called for MACC to provide immediate evidence to support its claims. -- AFP