Mr Simpson was aquitted of killing his ex-wife, but was found liable in a civil trial

She gave no details of Mr Simpson's connection to the investigation.

She said that eight people had been arrested and nine other homes searched in Miami, in the joint operation by the FBI, the US drug enforcement administration and the Miami-Dade police department.

Two arrests had also been made in Chicago.

Mr Simpson was seen walking in his garden, clad in a bathrobe, shortly after the agents arrived at around 0600 (1100 GMT) to trawl through his possessions, according to reports.

Televised trial

The search comes a month after Mr Simpson was cleared of assault and burglary in a road rage case, in which the charges carried a potential prison sentence of 16 years.

Police have responded three times to reported disturbances between Mr Simpson and his girlfriend, Christie Prody, since he moved to the southern Miami suburb of Kendall in early 2000.

Mr Simpson was acquitted of killing his ex-wife Nicole Brown Simpson and her friend Ronald Goldman in 1994, but was later found liable for the deaths in a civil trial.

He was ordered to pay $33.5m in damages.

His televised trial captivated public interest in America and around the world.

Nicole Brown Simpson and Ronald Goldman were stabbed to death in California in June 1994.