Syrian troops have stormed parts of the eastern city of Deir el-Zour and explosions can be heard throughout the area, according to activists.

An activist in the city told The Associated Press the military launched a pre-dawn raid today on the city, attacking it from four sides and so far taking control of eight neighbourhoods.

On Saturday, Syrian forces tightened a siege on the city of Hama, the main centre of the nearly five-month-old uprising against President Bashar Assad's regime.

The activist said the military raid on Deir el-Zour began at 4am this morning. The activist spoke on condition of anonymity, fearing reprisals.

The Local Co-ordination Committees, an activist group tracking the uprising, confirmed parts of the city were taken over by troops.

There was no immediate word on casualties.

Earlier the country's foreign minister tried to defuse protests by promising free elections by the end of the year.

Like previous reform promises, the new announcement is unlikely to have much resonance with Syria's opposition, which says it has lost all confidence in President Bashar Assad's overtures.

The four-year term of the current parliament expired earlier this year and Assad is expected to set a date for new legislative elections before the end of 2011.

Foreign minister Walid al-Moallem pledged to press ahead with reforms and said the new parliament "will represent the aspirations of the Syrian people".

"The ballot box will be the determining factor and it will be up to the elected parliament to review adopted draft bills to decide on them," he said during a meeting he held with Arab and foreign ambassadors in Damascus.

But Syria was coming under increasing international criticism over the bloody siege of Hama, launched last Sunday after residents calling for Assad to go took over the city of 800,000 and barricaded it against regime forces.

Gulf Arab countries broke their silence on the situation, calling for "serious" reforms in Syria. In a statement on its website, the six-nation Gulf Co-operation Council expressed deep concern and regret for "the escalating violence in Syria and use of excess force".

A spokesman said United Nations secretary general Ban Ki-Moon urged Assad in a phone conversation to stop the use of military force against civilians immediately.

In Damascus and other cities, mourners held funerals yesterday for several of those killed on Friday. Amateur videos posted online by activists showed crowds marching in the funeral procession of a teenager who was killed in the Damascus neighbourhood of Midan. Some of the mourners shouted "Allahu Akbar", or God is great, and "there is no God but God and Assad is his enemy".

Syria's state-run SANA news agency said funerals were also held for six soldiers and members of the security forces who were gunned down by "terrorist groups" and gunmen in Homs, Hama and the northern province of Idlib.

Last night security agents raided a house in a Damascus suburb where prominent opposition figure Walid al-Bunni had been hiding. They arrested Mr al-Bunni and his two sons, Iyad and Moayad, according to several rights groups and activists.

The London-based Observatory for Human Rights in Syria also said security forces arrested four activist brothers from the Khattab family after raiding their Damascus home.

Located 130 miles north of Damascus, Hama holds special significance for Syrians because of a 1982 massacre that sticks in the collective memory. In 1982, Assad's father, Hafez Assad, ordered the military to quell a rebellion by Syrian members of the conservative Muslim Brotherhood movement there, sealing off the city in an assault that killed between 10,000 and 25,000 people.

Syria-based rights activist Mustafa Osso said at least 24 people civilians died on Friday, most of them in Damascus suburbs when security forces opened fire during daytime protests and late-night demonstrations following evening Ramadan prayers. He said five were killed in Hama and its surrounding countryside.

The toll was confirmed by the Local Co-ordination Committees, a key activist groups tracking the Syrian uprising.