Tunis: A firefight between security forces and suspected Islamists holed up in a building in a Tunis suburb has left one policeman and up to four militants dead, the interior ministry said Tuesday.

The standoff, which began Monday afternoon, was not yet over, a ministry spokesman said, adding that so far a policeman and “between two and four terrorists” had been killed.

Special units of the Tunisian National Guard surrounded a building in the suburb of Raoued on Monday after a tip-off that “heavily armed” militants were inside the house, officials said.

Witnesses at the time said they had heard gunshots and had seen members of the security forces deploy in Raoued, not far from a popular beach in a Tunis suburb.

Tunisia has since the 2011 revolution been rocked by sporadic violence linked to militant Islamists who were suppressed under the regime of ousted strongman Zine Al Abidine Bin Ali.

The authorities laid the blame for the separate killings last year of opposition politicians Chokri Belaid and Mohammad Brahmi on Ansar Al Sharia, a radical Salafist group suspected of having links with Al Qaida.

Also last year, around 20 members of the security forces were killed during operations targeting a group of extremists in the Chaambi mountain region along the border with Algeria.

Interior ministry spokesman Mohammad Ali Aroui told reporters late Monday that the men holed up in the Tunis building had refused to surrender.

“Special units of the National Guard have surrounded a house where a terrorist group is located,” he said.

“There was an exchange of fire, and efforts have been made to try to take them alive ... [but] they don’t want to give themselves up,” he added.

The identities of the gunmen remain unknown and it is not clear how many remain inside the building.

Police have blocked access to Raoued, where an AFP photographer early Tuesday heard a gunshot ring out.