Ugandan police questioned two prominent opposition lawmakers accused of orchestrating a wave of grisly murders by machete-wielding gangs.

Villagers in Masaka region have been terrorised by thugs who police say have hacked to death up to 30 mainly elderly people in their homes at night in just two months. Ugandan police spokesperson Fred Enanga said 12 people had already been charged with murder and terrorism and another 11 were in custody.

He said some of the suspects told police that MPs Muhammad Ssegirinya and Allan Sewanyana had organised the attacks “to cause fear in the population and cause people to hate the government”.

The two men, who belong to opposition leader Bobi Wine’s National Unity Platform (NUP), were being questioned by police for a second day on Tuesday.

But Wine, the popstar turned politician whose real name is Robert Kyagulanyi, claimed the accusations were part of a plot by the government of President Yoweri Museveni to vilify the opposition.

“When the president said recently (the) opposition was behind the killings we thought it was a bad joke. But when the police summoned our MPs, we knew the grand plan by (the) regime to implicate NUP leaders in the killings was being implemented,” he said.

In an address last month Museveni described those behind the killings as “pigs” and vowed that they would be defeated. Museveni won a sixth term after a disputed election in January that Wine, who came second to the veteran leader and has repeatedly been targeted by the authorities, says was rigged.

“No matter what Museveni’s regime does, one day Uganda will be liberated and those framed for crimes because they are from the opposition will be freed,” Wine said. In Masaka, which lies southwest of the capital Kampala, residents demanded that the government take more action to stop the marauding killers.

“As we mourn our relatives who have been killed, we live in fear of being killed by the machete-wielding gangs,” said Sarah Kasujja, 45, a petty trader whose 81-year-old grandfather was among the victims.

“Some elderly people who have been living alone… have fled their homes for safety in towns,” she said.

“Government should take the blame for not defending us against the killers. The army and police have been deployed but they came too late.”

The head of the Uganda National Council for Older Persons, Charles Isabirye, described the wave of murders as a “shock to the nation”.

“For someone to kill old people who are living quiet lives in their homes is unbelievable,” he said.

“We demand of government to ensure protection for the older people in the countryside and the people behind (the killings) should be identified and punished.”

• An AFP report