Muluzi, the opposition United Democratic Front's candidate in the 2009 presidential election, was arrested at the main airport in the capital Lilongwe on Sunday after returning from a trip to Britain.

"Muluzi is being interrogated by police as we speak. He has been put under house arrest. His house has been searched, but I can't disclose what we have found to the public," Home Affairs Minister Ernest Malenga told Reuters.

A defence lawyer confirmed the raid on the Malawian politician's home in Blantyre and said Muluzi was confined to the premises.

"They have searched the house and found nothing, and we are still waiting for them to charge formally," defence lawyer Fahad Assani said.

Five members of Muluzi's UDF and three army generals were arrested last week on suspicion of being part of a plot to oust President Bingu wa Mutharika and put Muluzi into power. They have been released on bail.

An arrest warrant was issued at the time for Mules.

The UDF said that at least 10 of its supporters had been arrested and several injured in Lilongwe for protesting against Mucus's arrest. He had been scheduled to address a public rally there on Sunday.

Mules remains popular in the impoverished southern African nation for ending the rule of longtime strongman Hastings Kamas Banda in 1994 and paving the way for democracy. He held power until 2004 when he was replaced by way Maharaja.

The two, however, have fallen out over the president's anti-corruption drive, which has targeted some UDF members, including Mules. Way Maharaja quit the UDF to form the Democratic Progressive Party.

Mules was briefly investigated for corruption in 2006.