Saboteurs blew up a gas pipeline, state television said on Saturday, adding fresh turmoil to Egypt during unprecedented protests to end the 30-year rule of President Hosni Mubarak.

State TV quoted an official as saying that the "situation is very dangerous and explosions were continuing from one spot to another" along the pipeline which runs through North Sinai. "It is a big terrorist operation", a state TV reporter said.

A security source said the Egyptian army closed the main source of gas supplying the pipeline. Another security source in North Sinai said it was the Jordanian branch of the pipeline, not the one leading to Israel, blaming the attack on "foreign elements".

Israel Radio said the Egypt-Israel pipeline was not damaged, but the supply stopped as a precaution.

"We are looking into all the details but it is too soon to say how long supplies (from Egypt) will be affected," a source in the National Infrastructure Ministry told Reuters.

The blast in Egypt's North Sinai hit a pipeline carrying gas to Jordan, a security source in the area told Reuters. Israel gets some 40 per cent of its natural gas from Egypt, a deal building on their landmark 1979 peace accord.

The attack happened as demonstrations against Mubarak entered their 12th day, with no sign of an end to the confrontation which has pitted the 82-year-old leader against thousands of anti-government protesters.

Mubarak, who has pledged to step down in September, said on Thursday he believed Egypt would descend into chaos if he were to give in to protesters' demands that he quit immediately.

He has styled himself as a bulwark against Islamist militancy and essential actor in maintaining a peace treaty Egypt signed with Israel in 1979.

"Saboteurs took advantage of the security situation and blew up the gas pipeline," a state television correspondent said.

The SITE intelligence group, which monitors al Qaeda and other Islamist websites, said earlier this week some groups had been urging Islamic militants to attack the pipeline to Israel.

Al Qaeda, which has its ideological roots in Egypt, has been sidelined in the protests against Mubarak. The government in the past has used a perceived threat from Islamist militancy to justify its use of emergency laws which helped keep Mubarak in power.

State TV said the pipeline that was attacked supplied both the Israeli and Jordanian gas lines. Residents in the area also reported a huge explosion and said flames were raging in an area near the pipeline in the El-Arish area of north Sinai.

"Jihadists suggested that Muslims in Sinai take advantage of Egyptian unrest and strike the Arish-Ashkelon gas pipeline, arguing that it would have a major impact on Israel," SITE said.

With the unrest crippling the economy in Arab world's most populous nation, some Egyptians are anxious to return to normal. Banks were due to reopen on Sunday, the start of the week in Egypt, and the stock market on Monday.-Reuters