Police in Malaysia have stopped a speech by opposition leader Anwar Ibrahim to thousands of supporters in the capital, Kuala Lumpur, late Monday. Anwar is making a political comeback that is challenging the country's ruling coalition's 51-year grip on power. VOA's Luis Ramirez reports from our Southeast Asia bureau in Bangkok.

Former Malaysian Deputy Prime Minister Anwar Ibrahim waves to supporters as he arrives at a rally in Kuala Lumpur, Malaysia, 14 Apr 2008

For former Deputy Prime Minister Anwar Ibrahim, Tuesday marks his return to Malaysian politics from which he was banned after falling out of favor with the ruling coalition 10 years ago.

Analysts say the Barisan Nasional coalition - which has ruled Malaysia since independence in 1957 - sees Anwar as a real threat. James Chin is a politics professor at Monash University's Kuala Lumpur campus.

"Anwar is very much a symbol of the Reformasi movement," said Chin. "In other words, he's the symbol of the change that is sweeping Malaysia."

Anwar's People's Justice Party led the opposition to key victories in general elections last month in which the ruling coalition suffered the biggest losses in its history.

Anwar had been convicted of corruption and sodomy - charges his supporters say were politically motivated. He was imprisoned and later released in 2004, but was banned from politics.

On Tuesday, the restrictions on him expired, paving the way for him to run for office. Thousands of supporters gathered at a late night rally Monday in Kuala Lumpur for a countdown to the midnight expiration of the ban. The rally was held despite earlier warnings from police that such a gathering would be illegal because organizers did not apply for a permit.

Witnesses say that about 30 minutes into Anwar's speech, police went on stage and forced him to stop.

Later, at a news conference, Anwar said he has secured the support of enough defectors from the ruling coalition to form a new government. If he does, analysts say he could unseat current Prime Minister Abdullah Badawi.

Support for Mr. Badawi and the ruling coalition has eroded over corruption, rising crime, inflation and rising discontent among ethnic Indian and Chinese minorities. The groups complain the current system of giving preferences to majority Muslim Malays is depriving them of opportunities in business, education, housing and other benefits.

Professor Chin says these issues are at the core of Anwar's popularity.

"Anwar has come out and said that this is not the way to go and that the government cannot, or the country cannot, progress as long as you have this ethnic based system," he said. "So, he's presenting to the people a different type of system. He's saying that we should have a system that's fairer to all communities and that race should not be the deciding factor."

Anwar says he does not intend to run for any office in the near future. However, analysts predict his political profile is likely to continue to rise in the coming months.