KADUNA, Nigeria (Reuters) - Nigeria has deployed a special police force to restore calm in the northern state of Kaduna following communal violence that killed 55 people in the last few days, President Muhammadu Buhari said on Sunday.

The Kaduna state government imposed a 24-hour curfew on Sunday after violence broke out on the streets of the state’s capital city, also called Kaduna.

The violence in the state capital follows clashes between two communities in the Kasuwan Magani area of southern Kaduna which left 55 dead.

Locals said clashes broke out between Muslims and Christians in the area, around 50 kms (30 miles) from Kaduna city, on Thursday.

Hundreds of people have been killed this year in outbreaks of communal violence across Nigeria. Security has become a key campaign issue ahead of the February 2019 election in which Buhari will seek a second term.

“The violence in Kaduna ... is condemnable. The police have been authorized to do everything possible to restore calm. A Special Intervention Force has been deployed to the flashpoints,” Buhari said on Twitter.

Kaduna state’s police commissioner, Ahmad Abdur-Rahman, said earlier the clashes in the Kasuwan Magani area of southern Kaduna had led to 22 arrests.

“The federal government and its law enforcement agencies will work with the state government and community leaders to ensure the full restoration of peace and security,” Buhari said in another message on Twitter.

Police said the special force will carry out stop and search patrols, raid suspected criminal hideouts and make arrests in areas that have been flashpoints or considered to be at risk of violence.

Local people, who described unrest in both Christian and Muslim areas of the state capital, said troops were also seen on the city’s streets.

“This is a notice of a 24-hour curfew imposed on Kaduna town and environs, with immediate effect. Residents are advised to comply by this directive,” Kaduna state’s governor, Nasir El-Rufai, said on Twitter.

Clashes along ethnic lines have plagued southern Kaduna in the last few years. Last year troops and additional police officers were deployed to the state in response to an outbreak of violence.

Nigeria is Africa’s most populous nation with around 190 million inhabitants, split roughly equally between Christians and Muslims, and comprising around 250 different ethnic groups that mostly live peacefully side by side.