* Army leadership spilt between Hutu and Tutsi
* Burundi facing worst political crisis since end of war
By Patrick Nduwimana
BUJUMBURA, Feb 17 (Reuters) - Burundi's national army said on Monday it would not intervene in the worst political crisis to grip the east African country since a 12-year civil war ended nearly a decade ago.
Burundi, which has a complex power-sharing system between the majority Hutus and other minority groups, fought a deadly civil war that ended in 2005 during which the then Tutsi-dominated army fought against Hutu rebels.
The country was plunged into uncertainty earlier this month after three ministers from the minority Tutsi-led UPRONA party quit the coalition government when the president sacked his Tutsi deputy, also from UPRONA.
The turmoil deepened on Sunday when riot police clashed with members of UPRONA who were attending a meeting to vote on party leaders, firing tear gas to disperse the crowd.
The coalition government is set up under power-sharing arrangements that limit the majority Hutus to 60 percent of posts in the government and parliament, and guarantees the rest to the minority Tutsis.
Under the same arrangements, the army leadership is split between Hutus and Tutsis.
"There are rumours saying the army will interfere in the current crisis, we want to reassure that the army is united from the bottom to the top," defence minister Major General Pontien Gaciyubwenge told a news conference.
"The constitution demands police and army corps to observe neutrality and we have to respect that. Politicians have to resolve their problems and avoid involving defence and security forces in their business," he said, flanked by colleagues from the security, interior and justice ministries.
The departure of the three ministers has raised fears of greater ethnic tension in a country already reeling from more than a decade of war, and in a region already grappling with violence in eastern Democratic Republic of Congo, South Sudan and the Central African Republic.
On Friday, Burundi's President Pierre Nkurunziza appointed a deputy to his power-sharing cabinet, angering rivals who said the move was part of his plan to change the law and allow him to remain in power beyond the maximum two terms.
Critics say the new deputy, Prosper Bazombanza, backs plans to change the constitution.
Presidential and parliamentary elections are due in 2015. The presidency has made no comment despite several requests. (Writing by James Macharia; Editing by Catherine Evans)