Image copyright EPA Image caption Tension has been building in Aceh province, where authorities have begun imposing Islamic law on religious minorities

Two churches have been burned down and at least one person has been killed in clashes in Indonesia's Aceh province on Tuesday, say officials.

Report say hundreds of Muslim men attacked a church in Aceh Singkil district, setting it on fire.

A human rights group said the attackers then burnt down a second Roman Catholic church.

They then went to a third church, where a man died in clashes with Christians defending the church and the police.

Tension in Aceh has been rising amid increasing Islamic conservatism in the province and Indonesia as a whole.

Responding to the violence, Indonesia's President Joko Widodo tweeted: "Stop the violence in Aceh Singkil. Any background of violence, especially religion and belief, destroys diversity."

Last week, protesters calling themselves Aceh Youth Concerned for Islam held a demonstration demanding that what they claimed were unlicensed churches be torn down by authorities.

Image copyright EPA Image caption Police say the violence was brought under control and dozens of people were detained

Image copyright EPA Image caption The attackers demanded that churches that they said lacked permits be torn down

The local government had agreed to act, but on Tuesday tensions boiled over and the group took matters into their own hands.

"After burning the church, the mob tried to attack another church, but it turned out Christians were already at the ready," Aceh police chief Husein Hamidi told the AFP news agency, referring only to the first and third churches attacked.

"A clash occurred, and one man was killed after being shot in the head with an air rifle," he said.

It is thought that the dead man was part of the attacking group. Four people were also reportedly injured, one of them a member of the security forces.

In between those attacks, another Roman Catholic church was also burned down, according to human rights group Alliance of United North Sumatra.

Religious violence

Indonesia is the world's most populous Muslim-majority country, although it also has significant Christian, Hindu, Buddhist and Confucian minorities.

Aceh is the only province to have officially introduced Sharia law, which is increasingly being applied to non-Muslims too.

The district where Tuesday's attacks took place is a Christian enclave, though correspondents say some Christians have already left, fearing religious violence.

Another church was also burnt down in Aceh in August. And in July, a mosque was destroyed in the Christian-majority province of Papua, in eastern Indonesia, on the Islamic holy day of Eid al-Fitr.