Ugandan police have arrested 17 opposition politicians, including opposition leader Kizza Besigye, ahead of a planned protest over spiralling food and fuel prices in the capital Kampala.
A senior official from Besigye's party, the Forum for Democratic Change (FDC), said Besigye was arrested on Monday as he prepared to go to work.
"Besigye was arrested as he left his house this morning and is being held in Kasangati" police station on the outskirts of Kampala, said Alice Alaso, the secretary general of the FDC.
The co-ordinator of the protest, himself an opposition politician, told the AFP news agency that Democratic Party (DP) leader Norbert Mao and the head of the Uganda Peoples Congress (UPC), Olara Otunnu, were also arrested as they tried to join the movement.
"Mao was arrested metres from his gate while Otunnu managed to walk about half a kilometre before he was detained," said Mathias Mpuuga.
Besigye, who came a distant second in the February 18 election that was won by Yoweri Museveni, the president, had threatened to stage Egypt-style protests if the election was rigged.
He, however, stopped short of staging a protest after the results were announced though he dismissed the vote as fraudulent.
On April 11 Besigye was arrested, along with several opposition politicians, for taking part in a march dubbed "walk to work" where marchers refuse to use their cars as a protest against high fuel prices.
Besigye was freed after being detained briefly but vowed to press ahead with the protest.
Al Jazeera's Malcom Webb in Kampala said the high prices are an opportunity for the opposition to get people on the streets.
"People are unhappy; people are restless," he said.
Police spokesperson Judith Nabakooba confirmed the arrests and said they were in connection with the planned demonstration.
But Vincent Ssekate, the deputy police spokesperson, said Besigye was being investigated over a number of cases unrelated to the protests.
Besigye, 54, walked to church unobstructed on Sunday but his "walk to work" campaign has been roundly blocked.
Museveni has warned he will deal firmly with any unauthorised demonstrations and mocked Besigye in a press conference on Saturday.
"We made it clear to Besigye that you are not going to demonstrate or to walk. If you want to walk, go somewhere and take a walk," Museveni said.
Ugandan police on Thursday clashed with protesters in Kampala and several other towns as Besigye appeared bent on opposing the regime.
Protesters say steep prices are due to bad governance, but Museveni, who has ruled the east African country for a quarter of a century, insisted drought and foreign factors were to blame.
"Food prices have gone up because of unreliable rain and the bigger market in the region. Will the world prices go down because Besigye has demonstrated?" he said.
The consumer price index grew by four per cent in March from the previous month and the country's year-on-year inflation rate stands at 11.1 per cent.
Museveni argued that Besigye's opposition campaign risked destabilising the economy further and urged Ugandans to act responsibly and use fuel sparingly.