CAIRO (AFP) – Unknown saboteurs attacked an Egyptian pipeline supplying gas to Jordan, forcing authorities to switch off gas supply from a twin pipeline to Israel, an official told AFP.

The attackers used explosives against the pipeline in the town of Lihfen in northern Sinai, near the Gaza Strip, the official said. It was initially thought the pipeline to Israel was attacked.

"The pipeline to Jordan has been attacked and the supply to Israel has been cut off," the official said.

The army has taken precautionary measures to stop the fire from spreading, the official added, as rescue services were putting out the fire.

It was not immediately clear who was responsible, or whether the attack was linked to the deadly protests against President Hosni Mubarak's rule, which entered their 12th day on Saturday.

"We still don't have details of how it happened," he added.

Israeli public radio quoted an Egyptian official as saying the attack was carried out at dawn, using a small amount of explosives that caused only minor damage.

The fire lasted three hours and was under control, while gas supplies to Israel and Jordan were cut, the official said.

An armed Bedouin group in June threatened to attack the pipeline, security officials said, leading Egyptian authorities to beef up security around the pipeline and terminal.

Police relations with the region's former nomads are often tense, with the Bedouin complaining of routine harassment and discrimination.

Activists accuse the police of exploiting concerns about the pipeline to crack down on the community.

Human rights groups have criticised Egyptian policy towards the Bedouin, who faced harsh police treatment after a series of bombings in Sinai resorts between 2004 and 2006 which killed dozens of Egyptians and foreign tourists.

Egypt supplies about 40 percent of Israel's natural gas, and in December, four Israeli firms signed 20-year contracts worth up to 10 billion dollars (7.4 billion euros) to import Egyptian gas.

The attack came after Israel expressed concern that its natural gas supplies from Egypt could be threatened if a new regime takes power in Cairo.

"We again realise that the Middle East is not a stable region. We must act to ensure our energy security without relying on others," a spokesman for Israel's National Infrastructure Minister Uzi Landau said on Tuesday.

Israel is concerned that a post-Mubarak regime might not respect the bilateral peace treaty signed three decades ago -- potentially threatening the crucial energy supplies Egypt provides.

A broad swathe of Egypt's opposition, including the powerful Muslim Brotherhood, as well as public opinion, has called for Cairo to stop supplying Israel with gas.

Landau on Monday summoned the heads of Israeli companies that are developing the offshore Tamar gas field -- due to start production in 2013 -- to urge them to push ahead with its timely development, his office said.

Landau told them Tamar's importance was even greater "in these times of unrest in our region." The field, off the port city of Haifa in northern Israel, holds estimated reserves of eight billion cubic metres (280 billion cubic feet).

Israel's Globes financial newspaper reported that Landau's ministry had conducted exercises dealing with emergency scenarios in which gas supplies were cut off. It gave no further details.