* Bouteflika registers candidacy before March 4 deadline
* Incumbent likely to easily win if runs for re-election
* Another Bouteflika term means stability in short term (Adds details throughout)
By Lamine Chikhi and Hamid Ould Ahmed
ALGIERS, Feb 22 (Reuters) - Algerian President Abdelaziz Bouteflika, the aging independence veteran and Washington ally who suffered a stroke last year, will run for re-election on April 17, his premier said on Saturday, a vote likely to hand him a fourth term in power.
The announcement appeared to end months of speculation over Bouteflika's future after his medical trips to Paris intensified discussion of a succession after his 15 years in office.
Bouteflika, who opponents say is too frail to govern, was expected to announce his candidacy formally later on Saturday, with Prime Minister Abdelmalek Sellal running his campaign, a source close to the presidency said.
"Bouteflika will be a candidate," Sellal said in the northwestern city of Oran. "Bouteflika's decision to run comes at the insistence of the people and after some deep reflection."
State news agency APS said the 76-year-old leader had officially notified the Interior Ministry of his candidacy.
A potential transition in the major energy supplier to Europe would have come at a sensitive time with neighbours Egypt and Libya still deep in turmoil three years after the popular uprisings ousted their veteran rulers.
Backed by the ruling National Liberation Front (FLN) party, unions and other FLN allies, Bouteflika is almost sure to be re-elected, with opposition candidates unlikely to offer a serious challenge.
Loyalists see Bouteflika as the man who gave Algeria peace and economic stability after a civil war with Islamists in the 1990s that killed about 200,000 people. Many Algerians are wary of any upheaval after that bloody experience.
Opposition is still weak in Algeria. Since independence from France in 1962, senior FLN leaders and military officers, known in French as "Le Pouvoir (The Power)", have dominated politics, tussling among themselves for influence behind the scenes.
For months, speculation has been increasing about Bouteflika seeking re-election and whether he is healthy enough to run for a fourth term. A second visit to Paris in January for checkups prompted another round of succession talk.
In an apparent reference to opposition criticism about Bouteflika's health, Sellal said the president was in good health, and has all the "intellectual abilities and necessary vision" to carry out this responsibility, APS reported.
"He does not need to campaign himself, there are men who can campaign for him," the prime minister said.
But critics say Bouteflika, rarely seen in public since he returned from treatment in France last year, is too ill to run and should allow a new generation of leaders to take over.
One opposition leader had even called for Bouteflika to show his medical records before seeking office again.
In the short term, a Bouteflika mandate means stability for a partner in a U.S. campaign against Islamist militants in a region still struggling with unrest after revolts in other North African nations such as Tunisia, Libya and Egypt.
But Algeria also needs serious economic reform to attract more investment in its flagging oil and gas sector and to reduce restrictions on non-oil investment in an economy still shaking off years of centralised control.
An Islamist militant attack on an Algerian gas plant killed 39 foreign workers a year ago, worrying foreign oil companies already concerned about the tough terms Algeria has demanded in the past for its contracts.
Since late last year, Bouteflika had shored up his position by curtailing the influence of the chief of the DRS military intelligence agency, who in the past played political kingmaker.
Last month, the government sacked two DRS intelligence generals, in charge of domestic security and counter-terrorism, and a colonel, as Bouteflika's faction strengthened its hand against the military's influence. (Reporting by Lamine Chikhi and Hamid Ould Ahmed; writing by Patrick Markey; Editing by Alistair Lyon)