Bangladeshi troops say they have cleared a cafe in the capital Dhaka, where gunmen on Friday took at least 20 hostages, including foreigners.

They say 13 hostages, including four foreigners, were rescued and six attackers shot dead. However, the fate of other captives remains unclear.

Several of those held at the Holey Artisan Bakery cafe were believed to be Italian, and some may be Japanese.

The militant group Islamic State (IS) has said it carried out the attack.

Tuhin Mohammad Masud, a commander of the elite Rapid Action Battalion, said: "We have gunned down at least six terrorists and the main building is cleared but the operation is still going on."

Explosions and heavy gunfire were earlier heard, as the army and navy commandos stormed the cafe in the morning. They were backed by police and paramilitary Border Guards Bangladesh, officials told the BBC.

Armoured vehicles were also seen moving in the Gulshan neighbourhood.

The gunfire stopped after about an hour.

The identity of the rescued hostages and the fate of other captives believed to have been in the cafe was not immediately known.

At least two police officers were killed in earlier exchanges of fire late on Friday, and 30 police officers were injured.

Eight or nine armed men burst into the cafe in the diplomatic area of the city at about 21:20 (13:20 GMT) on Friday and opened fire.

A statement on the IS self-styled news agency Amaq said militants had attacked a restaurant "frequented by foreigners". It said that more than 20 people "of different nationalities" had been killed but this has not been confirmed.

Seven Italian nationals are believed to have been in the cafe, the Italian ambassador in Dhaka, Mario Palma, was quoted as saying by Italian media.

A Japanese government spokesman said Tokyo was investigating reports that some of its citizens were among the hostages.

The attack comes after a spate of murders of secular bloggers, gay activists, academics and members of religious minorities, blamed on Islamist militants.