Hundreds of members of Cameroon’s main opposition party are being held in custody after the country’s security forces carried out mass arrests during a series of anti-government protests over the weekend.

Two people were injured and 351 arrested on Saturday in four regions of the central African country in protests against its octogenarian president, Paul Biya, and his government. Several senior opposition leaders were among those arrested. Only a handful of people have been released.

The protesters’ demands included the release of their leader, Maurice Kamto, as well as hundreds of people arrested in earlier protests, and called for an end to the killings in the anglophone regions of the country, where a bloody conflict has played out over the last two years.

Kamto was arrested in January after protests against what he and his party, the Cameroon Renaissance Movement (MRC), say was a stolen election last October. He was later charged with insurrection, rebellion and “hostility to the homeland” by a military court, charges that theoretically carry the death penalty. Arrests have spiked in 2019, since Biya claimed a disputed landslide victory.

Saturday’s demonstrators also called for an investigation into what happened to the money for hosting the 2019 African Cup of Nations football tournament – a right Cameroon was stripped of because of delays in delivering the necessary infrastructure – and a revision of the electoral code.

“We were singing and asking them to free Mr Kamto and the other people, when they just came and asked us all to enter their vehicle,” said Samuel Kuetche, who was later released. “These people are heartless. We didn’t have any guns on us. We were not fighting anybody, but they forcefully took us to the police station.”

Opposition leaders said protest was a right enshrined in the country’s constitution.

Christopher Ndong, the secretary general of the MRC and one of the few leaders not behind bars, said: “It shows how dictatorial and how wicked [the government is] and how they are not willing to listen to the people. They shall continue arresting us because we shall not give up. You can’t be arresting people because you don’t want to listen to them.”

The situation in the anglophone north-west and south-west regions reached new depths last week with the killing of a four-month-old baby. Her parents were forced to flee after accusing state forces of killing her in a video, and are still in hiding. The government has not opened an investigation into the case.

Half a million people have fled their homes because of the violence, many of them crossing the border into Nigeria.

“Hundreds of villages have been burned, close to a million children are out of school, and tens of thousands are hiding in the bushes without any support. The international silence surrounding atrocities is as shocking as the untold stories are heartbreaking,” said Jan Egeland, the secretary general of the Norwegian Refugee Council, on a visit in April.

Another protest planned for next Saturday is expected to attract a higher number of people.