KUALA LUMPUR, Sept 21 (AFP) - The indefinite detention of ousted deputy premier Anwar Ibrahim sparked a second day of clashes here on Monday as Malaysia was put under the international spotlight.

Riot police battled with more than 1,000 people waiting in vain for Anwar outside the main courthouse after the police announced he would be held under the Internal Security Act (ISA).

Anwar's two right-hand men in the youth wing of Prime Minister Mahathir Mohamad's United Malays National Organisation (UMNO) together with four leaders of a Moslem youth movement which Anwar had once headed were also picked up under the draconian law, officials said.

Several thousand people congregated at Anwar's home amid threats of demonstrations at the national stadium, where Britain's Queen Elizabeth II was to close the 70-nation Commonwealth Games later on Monday.

The authorities threw up a huge security operation around the queen on the first full day of her state visit.

Mahathir also chaired a crisis meeting of UMNO to discuss the country's worst disturbances in three decades.

Police fired water cannon and tear gas to disperse crowds outside the central court building, waiting for the 51-year-old Anwar who was dismissed as deputy prime minister and finance minister on September 2.

At least 50 people were detained during three hours of street battles. One man running in the street brandishing a Malaysian flag was kicked and beaten as he was hauled away.

Police were later seen to beat onlookers and workers leaving their offices to return home.

The clashes broke out about half a mile (750 metres) from Parliament Square, where Mahathir and King Tuanku Jafaar gave a formal welcome to Queen Elizabeth with a 21-gun salute.

Outside the court, police repeatedly showered demonstrators with water laced with a pepper-like additive. Police gave several warnings to the Anwar supporters to clear shopping streets around the court building, which suddenly filled with tear gas as the authorities' patience ran out.

Police stormed Anwar's home on Sunday night and on Monday announced that he would be held under the ISA, which allows for indefinite detention without trial.

Anwar's wife, Wan Azizah Wan Ismail, who has taken up the campaign to bring down Mahathir, said she had real worries for her husband.

``I do not know what is happening to him. I fear for his life. Anwar must be freed. He is innocent,'' she told reporters.

Allegations of sexual misconduct and treason have been made against Anwar, who until recently had been Mahathir's heir apparent.

His adopted brother and a speech-writer were jailed for six months on Saturday after being found guilty of letting Anwar sodomise them.

Mahathir has said he is convinced the accusations against Anwar are true. Anwar has denied them and accused the prime minister of leading a smear campaign against him.

Mahathir chaired a crisis meeting of UMNO's ruling council which ran longer than expected amid denials by officials that several senior ministers and officials had resigned.

Mahathir called off a scheduled press conference to rush to the games closing ceremony. The sporting spectacular and the queen's visit have poured unwanted international attention on Malaysia as it struggles with the political troubles.

It emerged that Malaysian authorities were censoring television coverage of rioting in Kuala Lumpur taken by foreign broadcasters, the British Foreign Office said.

The BBC and Britain's independent television news channel ITN said that pictures taken of the unrest were being blanked from screens as they were transmitted to Britain. Television New Zealand also said its pictures were being blocked.

``We can confirm that this is happening and we are urgently pursuing the matter with the Malaysian authorities,'' a Foreign Office spokesman said.

Malaysia's neighbours viewed the latest twist in the saga with increasing alarm, calling for restraint.

Thailand and Japan both called for calm, saying they hoped for stability in Malaysia.

``Japan, which has a close relationship with Malaysia, hopes that the political situation in the country, which is making efforts to overcome its economic difficulties, remains stable,'' a foreign ministry spokesman said.

Australian Prime Minister John Howard said he was deeply concerned and warned against growing authoritarianism in the country, while Singapore's Senior Minister Lee Kuan Yew said he was hopeful the situation would not deteriorate.