Uganda's opposition Democratic Alliance has sharply condemned the arrest of two senior politicians and demanded their immediate and unconditional release.
Former prime minister Patrick Amama Mbabazi from the ruling National Resistance Movement (NRM) and Kizza Besigye from the opposition Forum for Democratic Change (FDC) were separately arrested Thursday.
The two are opponents of President Yoweri Museveni of the ruling NRM. Uganda plans to hold a general election next year.
Mbabazi was arrested on his way to a scheduled meeting with his supporters in Mbale, in the country's east. Police say he was arrested after refusing to cancel the meeting with his supporters, despite repeated warnings.
Besigye was arrested as he prepared to leave his home to launch a presidential bid for the FDC party nomination. Several of his supporters also were reported arrested.
Local media quoted Andrew Felix Kaweesi, police director of operations, as saying the arrests were carried out to prevent the two politicians from committing crimes.
Parliamentarian Mathias Mpuga, a leading member of the opposition Democratic Alliance, says the group has warned the government to end the practice of using state institutions to harass and intimidate them.
"Stop the brutality, stop the police partisanship and respect the constitution of the Republic of Uganda, and allow parties and individuals to organize and compete," said Mpuga. "We are waiting to listen to the response of the police and government on this matter because they know what they are doing is wrong, it is unconstitutional, it's an abuse of the rest of Ugandans, but they are adamant about it."
Police have previously said they would prevent Mbabazi from meeting his supporters because he has yet to receive approval from Museveni. But Mbabazi argued that because he is just an aspiring candidate, he does not need approval.
The opposition alliance has demanded that the government explains the arrests.
Mpuga says police were wrong to arrest the former prime minister.
"The position of the NRM constitution that they are quoting does not exist anywhere that for anybody to compete with Mr. Museveni then he has to get his tacit approval. But even if it was there, that position would be absolutely unconstitutional because everybody has a right to aspire for the position of their choice without being barred by any other law, because the constitution is very categorical about these issues," said Mpuga.