A Nigerian militant group on Saturday reiterated that foreign oil companies should leave the Niger Delta and threatened a planned trans-Saharan pipeline project.

In an e-mail, a spokesman for the Movement for the Emancipation of the Niger Delta, or MEND, warned companies still operating in the Delta, "namely Agip, Total (TOT), Shell and Exxon Mobil (XOM) to leave while there is still time because within the next 72 hours" it may launch new attacks.

Chevron Corp. (CVX) said on May 25 it had interrupted its onshore operations after a string of attacks on its pipelines.

The spokesman also said MEND "warns the investors to the Trans-Saharan Gas Pipeline project that unless the Niger Delta root issues have been addressed and resolved, any money put into the project will go down the drain."

On Friday, Algeria, Niger and Nigeria signed an agreement to kick off the process to build the $10 billion route, from where gas will be shipped to Europe.

"We will ensure that it faces the same fate other pipelines are facing today," the MEND spokesman said. He said the new threat came as a traditional ruler in the Delta was allegedly seized by the army.

The new warning comes after the government unveiled plans to pardon the militants.

The MEND spokesman said "armistice as against amnesty for freedom fighters is what MEND and Tompolo (a MEND leader) are favorably disposed to for adoption as the next step to take towards resolving the crisis."

-By Benoit Faucon, Dow Jones Newswires; benoit.faucon@dowjones.com; 44-20-7842-9266