Islamic State militants have seized the main government building in Ramadi, the capital of Iraq's largest province, BBC News reports.

As many as six suicide car bombs and mortars were used in the assault on the compound that houses the main police HQ and governor's office.

At least 50 security personnel are reported to have been taken prisoner at the site.

IS and Iraqi troops have been battling for months to take control of the strategically important Anbar province.

The attack by IS militants began overnight when the suicide car bombs were driven into compound housing a number of government buildings, killing at least 10 people and wounding a number of others.

Fighting continued into Friday, May 15, and by 14:00 (11:00 GMT) the black flag of IS was seen flying over the complex.

IS "now occupies the government centre in Ramadi and has also raised its flag over the police HQ for Anbar", a police major told the AFP.

The militant group itself issued a statement confirming it had taken control of the complex and said it had killed an unspecified number of pro-government fighters.

Fifty police officers are known to have been taken prisoner in the assault, but reports that they have been summarily executed are unconfirmed.

This latest assault is a blow for the Iraqi government which has been trying for more than a year to prevent Anbar and its key towns and cities from falling into the hands of IS.

The heavily-Sunni province of Anbar covers a vast stretch of the country west from the capital Baghdad to the Syrian border, and contains key highways that link Iraq to both Syria and Jordan.

Iraq's Prime Minister Haider al-Abadi pledged in April that his forces would "liberate" Anbar from IS after the success of re-taking Tikrit.

However, by Friday, the militant group had asserted its control over large areas of Ramadi and half of Anbar province.