Indonesian prosecutors said they would detain Indonesia's parliament speaker Akbar Tanjung after questioning him for seven hours at the attorney-general's office about graft allegations.

But plans to incarcerate the top politician hit a snag when he refused to sign documents relating to his own arrest, as required by Indonesian law.

Deputy attorney-general Suparman told reporters that Tanjung's refusal "to sign the dossiers of arrest is our current obstacle and that's what we are discussing right now. "For him to be detained anywhere he has to sign the dossiers of arrest. We have several legal options to consider but I don't want to disclose that," Suparman said. "God willing, he will be detained here at the cell of the attorney-general's office."

Prosecutors had earlier said Tanjung would be transferred to Salemba prison. At 9:30 pm Tanjung was still in a room at the attorney-general's office. There was no further information on whether or when he would be moved to a cell.

Tanjung, who has not been formally charged, also heads the former ruling Golkar party. He is the most senior political figure for years to be arrested over graft allegations. President Megawati Sukarnoputri promised to eradicate endemic corruption, collusion and nepotism when she came to power last July.

The issuing of the arrest warrant drew praise from Megawati's Indonesian Democratic Party of Struggle (PDIP) and threats from furious Golkar legislators. "The detention is part of the broader effort to enforce the law in accordance with the national assembly's resolution to eradicate corruption," PDIP deputy secretary-general Pramono Anung told AFP.

Golkar MPs declared they would pull their three members out of Megawati's cooalition cabinet. "We shall withdraw our ministers from the cabinet and withdraw our political support for Megawati Sukarnoputri," MP Idrus Marham was quoted as saying by the state Antara news agency.

Golkar, which ruled unchallenged for some three decades under former president Suharto, is now the second largest party in the 500-member parliament with 120 seats. PDIP has 153.

After his questioning ended in later afternoon, a pale and grim-looking Tanjung cancelled a press conference and tried to drive away with his bodyguards. But the compound gate was blocked by a paramilitary police truck and Tanjung returned to the attorney-general's office. His lawyer Ruhut Sitompul denied Tanjung had been trying to escape and said an arrest warrant had not been issued at that time.

The scandal centres around 40 billion rupiah (four million dollars) in state funds which were ostensibly allocated to feed poor people during the presidency of B.J. Habibie in 1999.

Tanjung, in his then capacity as state secretary, was in charge of the program. The attorney general's office says there is no evidence any food was ever delivered and there are suspicions that the funds were used to bankroll Golkar's campaign in the 1999 general election.