LAGOS, April 13 (Xinhua) -- Nigeria's police on Friday said it had arrested 12 more suspects in connection with the recent bank robbery in Offa town of central north Kwara state.

National police spokesperson Jimoh Moshood told reporters in Abuja, the country's capital, that the suspects had admitted to the various criminal roles they played in the robbery.

Moshood said items recovered from the suspects are two bareta pistols, 20 rounds of ammunition and four cell phones and SIM cards belonging to victims, some of whom were killed during the attack.

He said the suspects have previously been investigated and charged to court for armed robbery and cultism, noting that investigation was being intensified to arrest other suspects still at large.

According to him, the police will leave no stone unturned in unraveling this dastardly act and bring all those responsible to justice.

The police had earlier arrested nine suspects in connection with the robbery.

Armed robbers had attacked five commercial banks in Offa on April 5, during which 17 persons, including policemen and a pregnant woman were killed.

Nigeria's Inspector-General of Police, Ibrahim Idris, recently ordered the deployment of three units of Police Mobile Force (PMF), high powered police investigation team and Armored Personnel Carriers (APCs) to Kwara.