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The head of Algeria's largest political party on Monday questioned the leadership of the powerful chief of the nation's intelligence service and urged him to resign.

The comment by Amar Saadani of the National Liberation Front in an interview with the online news site Tout Sur L'Algerie hints at a major power struggle in the country ahead of April's presidential elections.

Mohammed "Tewfik" Mediene has headed the Department of Research and Security, as the intelligence service is known, since 1990 and is considered one of the main powerbrokers in this oil rich nation.

Algeria's incumbent president, Abdelaziz Bouteflika, a rival of Mediene's, is expected to run for a fourth term in office, despite being 76 and suffering from a stroke last year.

"After so many failures, in my opinion, Tewfik should resign," said Saadani, whom he also accused of fomenting unrest inside his party. Saadani listed a string of what he called intelligence failures under Mediene's watch, including the assassination of a president in 1992, the massacre of French monks in 1996, and more recently the January 2013 attack on a gas plant by al-Qaida linked militants.

A retired intelligence colonel said the party chief's statement was part of the struggle between the president and the intelligence chief to determine the outcome of the coming elections.

"Saadani's statements are aimed at further weakening the Department of Research and Security after it was reorganized by Bouteflika so that he will have the final say in succession," the retired colonel said, speaking on condition of anonymity because of the sensitivity of the subject.

Saadani is close to the president's family and has been one of the most vocal proponents of his running for re-election. While nominally a democracy with regular elections, power in Algeria is negotiated between the president and the heads of the military and intelligence services.