President Goodluck Jonathan has not yet said whether he will contest the polls, but most Nigerians expect him to do so, particularly given recent announcements from his administration - ranging from pledges to boost power supply to building more roads - that suggest he has plans beyond next January.

He named two northern politicians from the opposition All Nigeria Peoples Party (ANPP) as junior cabinet ministers on Wednesday, in what some analysts said looked like a move to undermine the cohesion of the rival party.

The cabinet approved the purchase of two Falcon 7X aircraft from France's Dassault Aviation and one Gulfstream G550 from the US planemaker for the presidential fleet at a cost of $150 million.

"After consideration, council approved the purchase," Information Minister Dora Akunyili told reporters after a cabinet meeting in the capital Abuja.

The first Falcon would be delivered towards the end of the year, with the second Falcon and the Gulfstream due to arrive by the second quarter of next year, after the elections.

The amount was already provided for in the 2010 budget but the timing of the announcement raised questions about the country's spending priorities.

The announcement comes a day after lawmakers approved plans to raise 88 billion naira ($585 million) via a bond issue to pay for the electoral commission to overhaul voter lists and buy additional ballot boxes for the elections.

The timing of the polls has broadly been known since the end of military rule a decade ago, and it was not immediately clear why enough funds had not been earmarked for the Independent National Electoral Commission (INEC) in the 2010 budget.

The Business Day newspaper said the supplementary INEC budget made Nigeria's voter registration process the most costly in the world. The daily Next newspaper questioned why 3 billion naira was earmarked for new vehicles: "Does INEC not already have vehicles," it pondered.

Government spending was already due to rise sharply this year. Parliament last month approved 445 billion naira in extra spending including pay rises for civil servants, doctors and professors.

That supplementary spending plan comes on top of the main 4.4 trillion naira 2010 budget, meaning Nigeria's fiscal deficit is expected to increase beyond 5.4 percent of GDP, well above a 3 percent target set just three years ago.

The Finance Ministry has warned that government revenues, mostly from oil sales, would not be enough to fund the budget and that the OPEC member would likely have to use up its windfall oil savings or borrow more.

Parliament last month passed a constitutional amendment bringing elections forward to January, leaving little time for reforms to avoid a repeat of chaotic 2007 polls.

An electoral roll riddled with fictitious names and omitting legitimate voters was one of the main problems at the 2007 polls, which were so marred by ballot stuffing and intimidation that observers deemed them not to have been credible.

INEC has said its spending plan is largely for the purchase of 120,000 electronic voter registration machines, including laptop computers, finger print scanners, cameras and printers to issue voter cards. (For more Reuters Africa coverage and to have your say on the top issues, visit: http://af.reuters.com/ ) (Writing by Nick Tattersall; Editing by Giles Elgood)