UPDATE 1-Nigerian president signs amended 2008 budget

(Adds details, analyst comment)

By Felix Onuah

ABUJA, April 14 (Reuters) - President Umaru Yar'Adua approved Nigeria's 2008 budget on Monday after weeks of bickering with the National Assembly over spending increases in sub-Saharan Africa's second-biggest economy.

Yar'Adua had twice refused to sign the budget, asking the Senate and House of Representatives to slash a 21 percent year-on-year increase in spending and give details of allocations to ministries, departments and agencies.

The National Assembly had first proposed raising government spending to 2.89 trillion naira ($22 billion), while Yar'Adua's initial proposal was 2.45 trillion.

The final approved spending figure was 2.74 trillion naira, while the reference price for crude oil was raised to $59, above the $54 proposed by Yar'Adua.

"The 2008 Appropriation Bill passed by the National Assembly was formally signed into law today," Yar'Adua's office said in a statement.

The dispute, resolved last week after both parties agreed to a supplementary budget to accommodate the spending increases, had raised political tensions and threatened to disrupt business in the world's eighth-biggest oil exporter.

"The reference price for crude has been raised ... (and) a number of other sources of additional spending have emerged," Standard Bank analysts said in a research note.