At least 26 people have been killed in clashes in Kyrgyzstan's second-largest city of Osh, officials say.

More than 400 people were wounded in the fighting, which is reportedly between Kyrgyz and ethnic Uzbek groups.

The cause of the clashes was not immediately clear. A state of emergency has been declared in the southern city.

Osh is home to a large ethnic Uzbek community and was the power base of former president Kurmanbek Bakiyev, who was overthrown in April.

According to local reports, fighting broke out between rival gangs and developed into gun battles late on Thursday.

The current situation demands self-restraint, wisdom and patience from all of us Roza Otunbayeva , Interim President In pictures: Kyrgyz unrest

Gangs of young men armed with metal bars and stones attacked shops and set cars alight.

Firefighters tried to put out the flames, but angry youths reportedly threw stones at them.

Local journalists say a group of young men attacked soldiers and took their weapons.

Residents say the shooting continued into Friday morning.

A number of buildings, including cafes, a local TV channel and a theatre, were also said to be on fire.

Many of the injured were being treated for stabbing and gunshot wounds, health ministry spokeswoman Yelena Bailinova told the Associated Press news agency.

Image caption Officials say the shooting has stopped

More than 40 were reported to be in a serious condition.

The interim government, which came to power after Mr Bakiyev's removal, has been struggling to impose order in the city ever since.

The leaders of Russia and China have appealed for calm.

The political crisis has raised fears of a civil war in the country, where both Russia and the US have military bases.

Gun battles

Interim President Roza Otunbayeva said those responsible for the violence were "trying to destabilise Kyrgyzstan and plunge it into fighting or conflicts".

She called on people to show restraint and "not yield to provocations".

It appears that the majority of the properties attacked belonged to ethnic Uzbeks.

In recent weeks, several incidents have prompted fears of inter-ethnic violence between Uzbeks and Kyrgyz.

The country's interior and defence ministers are reportedly travelling to the region.

Mr Bakiyev fled with his family to Belarus after clashes between government forces and protesters on 7 April, which left at least 85 people dead in the Central Asian state.

The violence was the culmination of months of discontent over rising prices and allegations of corruption in Kyrgyzstan, which had been regarded as one of the more progressive states in the region.

The interim government has promised to hold elections in October, after a constitutional referendum on reducing presidential powers.