"These are despicable acts in our society and must meet with utmost condemnation," Judge Arifin Jaka said.

He ordered the jail term to start only after Anwar has completed a six-year sentence for abuse of power imposed in April 1999.

The decision effectively dashes hopes of a political comeback by the charismatic Anwar, seen as Mahathir's natural successor until their dramatic falling-out.

A gasp of shock ran through the High Court but Anwar appeared calm.

"Thank you, your honour, you have completed Mahathir's plan," he told Arifin. "We'll meet again in 2014 or earlier."

Anwar, 53 on Thursday, says he is the victim of a political conspiracy masterminded by Mahathir because he was seen as a political threat and had intended to expose corruption.

Mahathir, aged 74 and in power since 1981, denies any plot.

In a defiant statement Anwar accused his former mentor of cowardice, destroying the judicial system and trying to protect the interests "of his greedy family and cronies."

Shouts of "Long live Anwar" and "Destroy Mahathir" rang out as he left later in a police van, waving and smiling.

Some 500 police -- backed up by a dog unit, mounted police, a helicopter and a water cannon -- were on duty. At one point the crowd, gathering in defiance of a ban on public assembly, numbered around 1,000.

Eight people were arrested, including activist Tian Chua, but no major clashes broke out.

Some 100 supporters shouting "Reformasi!" (reform) gathered later in a main shopping street but fled when helmeted riot police armed with batons advanced on them.

Anwar and Sukma Darmawan, his 39-year-old adopted brother, were convicted of sodomising Azizan Abu Bakar, a former Anwar family chauffeur, between January and March 1993.

Sukma was also convicted of abetting Anwar in committing sodomy, seen as a serious crime in this mainly Muslim country.

Sukma was sentenced to six years in jail and four strokes of the cane but was granted bail pending an appeal.

Without remission, Anwar will be in jail until 2014. With the customary one-third remission he could be free in 2009 but cannot stand for parliament for five years after his release.

His wife Wan Azizah Wan Ismail wept after the sentence. Three of their daughters were in the courtroom.

"We are shocked and very angry," said eldest daughter Nurul Izzah. "We never expected it to be so cruelly done. The fight will go on."

Wan Azizah, fighting to keep her composure, told reporters: "Even though I had expected it, it does not soften the pain, the anguish, the shock and dismay.

"It is a cruel sentence."

She said Anwar would appeal.

"This will send shockwaves throughout the nation, throughout the world," said lead defence counsel Christopher Fernando.

"It's a black day for justice in Malaysia," said Mahfuz Omar, youth chief of the opposition Parti Islam SeMalaysia.

Local and international rights groups also criticised the sentence.

Amnesty International said it considered Anwar a prisoner of conscience who was prosecuted "because of his dissenting political activities and the challenge he posed to government leaders."

Anwar, sacked by Mahathir as deputy premier and finance minister in September 1998, read a statement accusing Arifin of working to "the pre-ordained script" of conspirators led by Mahathir.

The premier, he said, "is a coward who would not take responsibility for his own evil.

"So he uses the courts and with the same stroke he completes the destruction of the judiciary."

Anwar said he was persecuted because he objected "to the use of massive public funds to rescue the failed businesses of his (Mahathir's) children and cronies."

"This (my conviction) is a small sacrifice to pay in the cause of democracy and justice but I worry for the nation. Corruption is endemic, the pillars of democracy, civil society and the rule of law are shattered.

"To Dr. Mahathir and his greedy family and cronies, I say, beware the wrath of the people."

The two-year Anwar drama divided the country and eroded support for the ruling party in last November's elections.