Nigeria's government is making "no meaningful effort" to rescue more than 250 children abducted from a Catholic boarding school in the central state of Niger last Friday, the main Catholic cleric in the region has told the BBC.

But Bishop Bulus Dauwa Yohanna's accusation was disputed by the state's police chief, who accused the school of failing to cooperate with its search and rescue operations.

It is unclear who abducted the children from St Mary's school in Papiri village, but criminal gangs have been involved in kidnappings for ransom across Nigeria.

US President Donald Trump has threatened to intervene militarily in Nigeria if the government fails to stop "the killing of Christians".

Nigeria is the most populous state in Africa, with a large Christian and Muslim population.

Its government says that people of all faiths and no faith are victims of insecurity in the country.

Militant Islamist groups are also waging an insurgency in Nigeria, with the government confirming last week that a senior army general had been killed by jihadists in an ambush in north-eastern Borno state.

US Secretary of War Pete Hegseth held talks with Nigeria's National Security Adviser Mallam Nuhu Ribadu last week to discuss ways to make "tangible progress on stopping violence against Christians in Nigeria and combating West African jihadist terrorist groups", the U.S. Department of War said in a statement.

Nigeria's presidential spokesman Bayo Onanuga said that Ribadu's delegation refuted allegations of state-sanctioned religious persecution in the West African state, and said that the security crisis was driven by criminality, extremism and land-related conflicts.

Mr Onanuga added that the two governments had agreed to set up a working group to focus on strengthening defence and security cooperation.

The Niger state chapter of the Christian Association of Nigeria (CAN) says that 303 students and 12 members of staff were abducted from the school in Papiri village, but 50 children managed to escape and have been reunited with their families.

Bishop Yohanna - who is the chairman of the Niger chapter of CAN and leads the Catholic church in the region - told the BBC that the only official action taken so far to rescue the students had been to compile their names.

"I'm not aware of any effort made by government beyond collecting the names of the students from us," he said.

He disputed allegations made by the governor of Niger state, Umar Bago, in local media that the church had defied an order to close its school after threats of attacks.

"We did not receive any order at any point," the bishop added.

Responding to criticism about the presence of police in Papiri, Niger state police chief Adamu Abdullahi Elleman said enough had been deployed despite the fact that the BBC only saw three officers at the school.

The BBC also drove about 60km (37 miles) from Yauri, a major link road to Papiri, but came across only one police checkpoint and none of the officers was armed.

However, the police commissioner insisted that a tactical police team and members of other security agencies were stationed in the community.

He said the police headquarters in Agwara town, not far from Papiri, had been made the operational base.

"So they moved from Agwara police station to the school. Probably when you got there, they must have moved back to the headquarters," the police commissioner told the BBC.

He stressed that a search operation for the children was continuing, but said the school was yet to "report" to his command.

Meanwhile Nigeria's police chief Kayode Egbetokun said that he had stepped up operations, including on the intelligence front, to ensure the children and members of staff were freed.

"We are ready to give everything to ensure that the remaining pupils and their teachers still in captivity are rescued unhurt," he said, in a statement issued after talks with the state governor.

The abduction at the school was the third to hit Nigeria in a week, forcing President Bola Tinubu to cancel his trip to the G20 summit, held in South Africa at the weekend, to deal with the crisis.

On Tuesday, Mr Onanuga said that 24 girls who were kidnapped last week from a boarding school in Kebbi state, which borders Niger, had been released.

The presidential spokesman did not give details of how their freedom was secured.

Tinubu said on Sunday that 38 worshippers abducted from a church further south in Kwara state had also been released.

Two people were killed in the attack on the church.

The spate of abductions has forced the closure of many boarding schools across Nigeria, with parents rushing to collect their children.

The authorities in Lagos - the most populous state in Nigeria - said they were beefing up security at schools, places of worship and other key buildings to prevent attacks.

Additional reporting by Chris Ewokor, Abayomi Adisa and Gift Ufoma