DUBAI (Reuters) - The Qatar-based news channel Al Jazeera said on Friday its signal was being jammed on several frequencies and its website had been blocked in Libya.

Al Jazeera, whose coverage of the political unrest in the Middle East and North Africa is widely watched in the Arab world, reported the jamming on its website where it offered alternative frequencies on the Arabsat, Nilesat and Hot Bird satellites.

Al Jazeera has closely followed events in Libya, Bahrain and Yemen, contacting protesters and government backers by telephone and often using footage of events sent via the Internet.

Bahraini security forces fired on protesters on Friday, wounding dozens, and thousands of people demonstrated in Libya after a deadly government crackdown as pro-democracy unrest in the Middle East and North Africa turned increasingly violent.

Earlier this month, Al Jazeera complained of similar jamming and Egypt's Nilesat cut off its signal for more than a week after the Egyptian authorities ordered the channel to stop operations in the country during the unrest that ended President Hosni Mubarak's 30-year rule.

Launched in Qatar in 1996, Al Jazeera has more than 400 reporters in over 60 countries, according to its website. It says it can reach 220 million households in more than 100 countries.

(Reporting by Firouz Sedarat; editing by Andrew Dobbie)