Tehran, Dec 28 - The nephew of Iranian reformist opposition leader Mir-Hossein Moussavi was among those killed during protests in Tehran, the opposition claimed Sunday - one of several people apparently killed during a day of demonstrations across the country which also saw at least 300 people arrested.

After a confusing day of rumour, denial and counter-rumour, there was no official confirmation of the death of Ali Moussavi. Some reports said he died after being shot in the chest.

Despite initial denials from Iranian police of any fatalities, Iran state television late Sunday evening confirmed that there had been some deaths during the day of protests.

That was the first such official confirmation of any deaths of anti-government protestors since those that followed the disputed presidential election in June.

According to a police report, a total of five people died in "rioting" Sunday.

Deputy Police Cheif Ahmad-Reza Radan told state television said the total was only four, although around 300 demonstrators had been arrested.

Radan claimed that of the four dead, one had been shot, one had fallen from a bridge, and a two had died in car accidents.

He insisted that the police had not been armed.

However, the reformist opposition to the ultra-conservative President Mahmoud Ahmadinejad claimed that four protestors, including Ali Moussavi, were killed in the capital, Tehran.

The opposition Internet site Jaras additionally claimed that four more protestors had been killed in the north west of Iran.

Opposition groups had announced that they would take advantage of the weekend's annual mourning ceremonies of Tassua and Ashura -marking the martyrdom of the third Shia Imam Hossein - to protest against President Mahmoud Ahmadinejad.

Moussavi, a former prime minister, was one of the defeated candidates in those presidential elections.

According to witnesses, the protesters numbered several thousand in Tehran, many arriving by train, whilst motorists honked their horns to show support.

Numerous police motorbikes were also set ablaze, witnesses reported.

The official Fars news agency reported that supporters of Moussavi had set fire to a Koran, and pelted stones at a religious ceremony.

Despite the police denial, there have been pictures distributed by opposition supporters allegedly showing protestors either dead or severely injured.

According to witnesses, opposition supporters in central and western Tehran burned police motorbikes and trash cans while shouting "Death to the Dictator".

The protests were reportedly held near Tehran University in the city's centre, which was the scene of protests and clashes Saturday as well. (IANS)