JAKARTA • Indonesian police shot dead four men after they used samurai swords to attack officers at the Riau provincial police headquarters in the city of Pekanbaru in Sumatra yesterday, days after a wave of deadly suicide bombings in another part of the country.

National police spokesman Setyo Wasisto told a briefing that the men had slammed a minivan into a gate at the station before getting out to stage the attack.

Inspector-General Setyo said a police officer was killed after one of the perpetrators tried to escape and crashed into him, while two officers were wounded in the attack.

"The one who escaped has been captured and secured at Pekanbaru police station," he said.

An internal police report said one of the dead men in the Pekanbaru attack had a suspected bomb strapped to his body, although Insp-Gen Setyo did not comment on this.

Television images showed what were reportedly the bodies of four suspects lying on the ground. There was a long sword next to one body.

A journalist who had been at the police station yesterday was also hurt after being hit by the car. A press conference about a drug bust was under way when the attack took place.

The Islamic State in Iraq and Syria (ISIS) militant group, which claimed responsibility for the series of recent attacks in East Java province, said it was also behind the Pekanbaru attack, according to the group's Amaq news agency. It offered no evidence in support of the claim.

Insp-Gen Setyo said the men belonged to the Islamic State of Indonesia network in Riau, or NII, "which is part of the ISIS network in Indonesia".

Police said three of the Pekanbaru attackers were Riau residents aged between 26 and 42.

Four of the men involved in the attack had previously tried to help terror detainees who were rioting at a maximum-security police lock-up outside Jakarta last week, he said.

It was not clear, however, if the four were the same men shot dead by police yesterday.

Insp-Gen Setyo said they had travelled from Sumatra to help the rioters, but returned as the situation had been defused.

The attack comes as Indonesia has been rocked by deadly attacks on churches and a police station in the city of Surabaya, in East Java province, over the past few days that have left more than 20 people dead, including 13 suspected perpetrators. The multiple suicide bombings were carried out by families who had even included their young children.

An explosion also occurred on Sunday at an apartment in neighbouring Sidoarjo regency, where militants were suspected to have been constructing bombs, police said.

The attacks were the worst in the world's biggest Muslim-majority country since the bombing of tourist-packed restaurants in Bali in 2005.

Police suspect the East Java attacks were carried out by a cell of the Jemaah Ansharut Daulah (JAD) militant group.

JAD, an umbrella organisation that is believed to have drawn hundreds of Indonesian sympathisers of ISIS, is on a United States State Department terrorist list.

Although the NII is separate from the JAD group, Insp-Gen Setyo said they were both part of the wider pro-ISIS network in Indonesia.

"They all pledged allegiance to (ISIS leader) Abu Bakr al-Baghdadi," he said.

Indonesia - which is set to host the Asian Games in three months and an International Monetary Fund-World Bank meeting in Bali in October - has long struggled with Islamist militancy, including the 2002 Bali bombings that killed more than 200 people - mostly foreign tourists - in the country's worst terror attack.

After some major successes tackling Islamist militancy since 2001, Indonesia has seen a resurgence in recent years, including in January 2016, when four suicide bombers and gunmen attacked a shopping area in the capital Jakarta.

Police have been frequent targets of mostly low-level attacks by local militants, including a suicide bombing at a bus station in Jakarta last year that killed three police officers.

This week's bloody violence is putting pressure on lawmakers to pass a stalled security law that would give police more power to take pre-emptive action against people suspected of planning terror attacks.

Indonesia's elite anti-terror force Densus 88 has responded with a series of raids in which several suspected militants have been shot dead - including the second-ranking member of the JAD cell in Surabaya.

Meanwhile, the police anti-terror squad yesterday arrested three militants on the outskirts of Jakarta. During the arrest, the police seized an ISIS flag and scores of weapons, local media quoted a police official as saying.

REUTERS, AGENCE FRANCE-PRESSE JAKARTA POST/ASIA NEWS NETWORK, XINHUA