More than 300 children and staff are now thought to have been kidnapped by gunmen from a Catholic school in central Nigeria, making it one of the worst mass abductions the country has seen.

The Christian Association of Nigeria said 303 students and 12 teachers were taken from St Mary's School in Papiri, Niger state - substantially more than previously estimated.

It said the figures have been revised upwards 'after a verification exercise'.

The kidnapping comes amid a surge of attacks by armed groups. The revised number of people taken surpasses the 276 abducted during the infamous Chibok mass abduction of 2014.

Local police said armed men stormed the school at around 02:00 local time on Friday morning, abducting students who were staying there.

Dominic Adamu, whose daughters attend the school but were not taken, told the BBC: 'Everybody is weak... it took everybody by surprise.'

One distressed woman tearfully told the BBC that her nieces, aged six and 13, had been kidnapped, adding: 'I just want them to come home.'

Police said that security agencies were 'combing the forests with a view to rescue the abducted students'.

It was initially reported that 215 pupils had been taken, but that figure has since been revised upwards. The new number is believed to be almost half of the school's student population, the news agency AFP reports.

Authorities in Niger state said the school had disregarded an order to close all boarding facilities following intelligence warnings of a heightened risk of attacks. They said in a statement the move exposed pupils and staff to 'avoidable risk'. The school has not commented on that claim.

The kidnapping of people for ransom by criminal gangs has become a major problem in many parts of Nigeria. The payment of ransoms has been outlawed in an attempt to cut the supply of money to the criminal gangs - but this has had little effect.

Friday's mass abduction was the third such attack in the country in a week. On Monday, more than 20 schoolgirls were kidnapped from a boarding school in neighbouring Kebbi state. A church was also attacked further south, in Kwara state, resulting in fatalities and further abductions.

Nigerian President Bola Tinubu has postponed his foreign trips, including to this weekend's G20 summit, to address security concerns. The central government has ordered more than 40 federal colleges to close and public schools in some states have been shut due to the rising insecurity.

The mass abduction follows claims by right-wing figures in the US, including former President Trump, that Christians are being persecuted in Nigeria – an allegation the Nigerian government has dismissed.

Campaigners and politicians in Washington have alleged that Islamist militants are systematically targeting Christians in Nigeria, a claim contested by Nigerian officials.