Uganda opposition leader Kizza Besigye, third left, and his supporters were blocked on their way to protests [Reuters]

Ugandan police have arrested opposition leader Kizza Besigye for the second time in a month, as he was leaving his house to join a protest against soaring food and fuel prices, his party has said.

Anne Mugisha, a senior official at Besigye's Forum for Democratic Change, said his exact place of detention was unclear after being moved from different police stations.

"Besigye ... was taken in a police vehicle and his driver chased them but he lost them as they entered a police barracks," Mugisha said.

"Up to now we don't know where he is and we're calling it an abduction."

Judith Nabakooba, a police spokeswoman, said Besigye was taken to the criminal investigations department of the police headquarters in nearby Kampala, Uganda's capital.

Nabakooba said that Besigye was walking along the road with more than 20 people and was thus disturbing traffic.

"He walked with over 20 people including journalists from his home," she said.

"Police stopped him when he was on the road and advised him not to walk with such a big number of people on the road because it disturbs traffic but Besigye insisted that he had to walk to wherever he wanted."

The authorities had briefly detained Besigye, a one-time presidential contender, earlier this month when he joined a 'walk-to-work' protest on the outskirts of the capital, Kampala.

Deadly protests in April and May over high food and fuel prices were crushed by President Yoweri Museveni, who has been in power for more than two decades, and who blames the high costs on outside pressures.