U.S. Secretary of State Hillary Clinton said on Wednesday that an Arab League monitoring mission in Syria cannot continue indefinitely and dismissed a recent speech by Syrian President Bashar al-Assad as chillingly cynical.

Instead of taking responsibility, what we hear from President Assad in his chillingly cynical speech yesterday was only making excuses, blaming foreign countries, conspiracies, Clinton said during a news conference with Qatar's Prime Minister Sheikh Hamad bin Jassim al-Thani.

Clinton said the Assad government had not fulfilled its promises to halt the violence, release prisoners and withdraw security forces from urban areas.

I think it's clear to both the prime minister and myself that the monitoring mission should not continue indefinitely. We cannot permit Assad and his regime to have impunity, Clinton said, adding that the United States and its Arab allies would await the final report on the monitoring mission when its mandate concludes on January 19.

Al-Thani, who also serves as the Gulf state's foreign minister, said doubts were growing about the effectiveness of the monitors.

I could not see up until now a successful mission, frankly speaking, al-Thani said, adding that the final report following the mission's January 19 conclusion could help guide the next steps on the crisis.

This report will be very important for us to make the right judgement, he said. We hope we solve it, as we say, in the House of the Arabs but right now the Syrian government is not helping us.

Clinton's comments followed a decision by the Arab League to delay sending more monitors to Syria after this week's attack on an observer team in the port city of Latakia in which 11 observers were lightly injured. [ID:nL6E8CB5O5].

In his speech on Tuesday, Assad mocked the Arab League, vowed to hit terrorists with an iron fist and promised reforms, but with no hint that he would relinquish the power he inherited from his father in 2000.

The Arab League, which suspended Syria in November for failing to halt its crackdown on protests, sent its observer mission in December but it has not stopped the bloodshed.

(Reporting By Arshad Mohammed and Andrew Quinn; Editing by Sandra Maler and Cynthia Osterman)