* 5-Star Movement wants jet purchase eliminated
* Political momentum against jet is building
* Government needed to make decision on fighter
By Steve Scherer
ROME, April 9 (Reuters) - Italy's 5-Star Movement, led by comic Beppe Grillo, wants to scrap the country's planned purchase of 90 Lockheed Martin Corp F-35 fighter jets and use the savings to help boost the struggling economy, a lawmaker told Reuters on Tuesday.
Italy has been unable to seat a government since the February national election that left no single force with a working majority in parliament, but 5-Star wants to form parliamentary committees so laws can be made without one.
"We plan on presenting soon a motion in parliament to totally abandon the F-35 programme," Alessandro Di Battista, a 5-Star deputy in the lower house, told Reuters.
Eliminating the purchase of the fighter jets would save Italy a total of an estimated 10 billion euros ($13 billion)but it would leave the Air Force and the country's new aircraft carrier with an outdated fighter fleet.
Even though support for the purchase of the fighter, built by Lockheed Martin Corp of the United States is dwindling, any decision to drop or curtail the procurement is not likely to be taken before a government is formed.
The troubled F-35 is seven years behind schedule and 70 percent over early cost estimates, and orders for the super technological new jet have been cut during an economic crisis that has shrunk defence budgets worldwide.
Last year, Italy cut its F-35 order to 90 warplanes from the 131 it had agreed to buy more than a decade ago, a move it said would save 5 billion euros. The package also includes maintenance work for Italy's state controlled defence technology group Finmeccanica.
The 5-Star Movement does not have enough votes in parliament to shoot down the jet purchases on its own, but political momentum against the Joint Strike Fighter is building.
The Left Ecology Liberty (SEL) party has already presented a motion to parliament against the fighter-jet purchase, and the Democratic Party (PD) has said it is in favour of further reductions.
"Even in Washington they know the F-35 is a fighter that cannot fight, but in Italy we're still trying to buy it," Nichi Vendola, head of SEL, told Reuters, referring to the technical problems that have dogged the jet.
Vendola said the money saved should be used to improve schools, the nation's aqueducts and to increasing public day-care programmes for children.
The PD has already said the F-35 purchases should be "rethought," Lapo Pistelli, the party's top foreign affairs advisor, told Reuters. "But this is a decision that must be taken by a government with full powers."
On Wednesday, the 5-Star Movement will ask parliament to back the immediate withdrawal of Italian troops serving under the umbrella of the North Atlantic Treaty Organisation in Afghanistan, Di Battista also said.
"It's an unacceptable, shameful war," he said.
Currently, Italy's more than 4,000 troops are to be drawn down by 25 percent this year, with the rest coming home by the end of next year, and it costs Italy about 750 million euros per year.
Parliament must approve continued funding for the mission later this year.
Though the 5-Star does not want Italy to withdrawal from NATO, Di Battista said: "Any historic agreement can be discussed. If something is unjust, then we need to rethink it." ($1 = 0.7658 euros) (Reporting by Steve Scherer; Editing by Michael Roddy)