Two people on a motorbike have carried out a suicide bombing at a police HQ in Surabaya, a day after a wave of deadly blasts in the Indonesian city.

Police officers were injured in the explosion, which occurred at 08:50 local time (01:50 GMT), but the extent of casualties was not immediately clear.

At least 13 people were killed in bomb attacks on three churches on Sunday.

The Islamic State group has said it was behind those attacks.

Authorities said they would provide more details about the latest attack at a briefing later.

It was not yet clear whether the attacks were connected to deadly blasts on Sunday.

In those, a mother and two daughters blew themselves up at a church, while the father and two sons targeted two others.

Police say the family were among hundreds of Indonesians who had returned from Syria, where IS has been fighting government forces. No details were given about the family's alleged involvement in that conflict.

The bombings are the deadliest in Indonesia in more than a decade, and also left more than 40 people injured.

Aida AYSA,

“Khalg gazeti”