Nigeria's best known rebel group on Saturday threatened to thwart a 10-billion-dollar trans-Saharan gas pipeline linking vast reserves in Nigeria to Europe, but the army vowed to protect the project.

"Any money put into the project will go down the drain as we will ensure that it faces the same fate other pipelines are facing today," the Movement for the Emancipation of the Niger Delta (MEND) said in an email statement.

On Friday, three African countries -- Algeria, Niger and Nigeria -- signed a deal in Abuja to build the more than 4,000-kilometre (2,485-mile) pipeline conveying gas destined for the European market from the Niger Delta in Nigeria, via Niger and Algeria.

No date was announced for the start of construction, but the first delivery of gas is scheduled in 2015.

The Joint Task Force (JTF) tasked with protecting oil firms and personnel in the region, said it would not allow the militants to thwart the project.

"The JTF will protect and secure any oil and gas installations in the country. MEND is merely ranting. They cannot succeed," JTF spokesman Colonel Rabe Abubakar told AFP.

MEND urged oil firms still operating in the restive Niger Delta to leave immediately, threatening -- in coded language -- to carry out new attacks within the next three days.

"Within the next 72 hours Hurricane Piper Alpha will be upgraded to Hurricane Moses," it warned.

The group also accused the JTF of abducting a traditional ruler of the area, saying Isaac Thikan, the Agadagba of Egbema and a staunch critic of the military, was abducted on June 24 and taken to JTF headquarters in Effurun, Warri.

Abubakar also refuted the abduction allegation, describing it as "untrue and baseless".

"The military have never kidnapped anybody not to talk of a traditional ruler. We respect the traditional institution and will do everything to protect and preserve it," he added.

He advised the militants to drop their guns and embrace an amnesty offer by government in the interest of peace and development of the country.

President Umaru Yar'Adua has given the rebels up to October 4 to accept an unconditional pardon as part of efforts to end the unrest in the volatile oil-producing south.

MEND, which came to prominence in December 2005, has claimed responsibility for many violent attacks on oil firms and interests in the past few months.

The unrest in the Niger Delta has reduced Nigeria's oil exports to 1.8 million barrels per day, from 2.6 million in 2006.