The Arab League has said it will be imposing further diplomatic and economic sanctions on Syria following a day of continued violence against protesters.

The sanctions include a travel ban and the freezing of assets for 19 senior officials.

The news comes as opposition groups claim that 25 more people have been killed in clashes on Saturday between the Free Syrian Army, made up of army defectors, and forces still loyal to the regime. The worst violence reportedly centred on the city of Idlib.

No western journalists are allowed in Syria, so reports remain unconfirmed.

Last Friday, a deadline passed for the Syrian government to allow Arab League monitors into the country to mediate between the regime and the protesters. Although Syria agreed in principle to the monitors, that have so far failed to honour the commitment.

Demonstrations against President Bashar al-Assad began in March and were met by a brutal crackdown, which triggered further unrest.

Since then the violence has steadily increased, with Navi Pillay, the UN High Commissioner for Human Rights, recently assessing the country to be in a state of civil war.

On Friday, US Vice President Joe Biden warned that the bloodshed in Syria threatened to fan the flames of sectarian conflict.

In comments that appeared in the Turkish daily Hurriyet, Biden said: "We stand with Turkey and a growing chorus of nations in calling for President Assad to step aside."

The new sanctions, which were settled upon following a meeting of Gulf state ministers in Qatar, will affect politicians, members of the intelligence community and those believed to be involved in the crackdown.

Restrictions already in place have severed transactions from Syrian banks, while flights between Syria and Arab League countries will be suspended on the December 15.

According to the UN, 4,000 people have been killed since the uprising began, with nearly 1,000 believed to have died in November alone.