Nairobi - Burundi on Monday began the process of withdrawing its troops from the African Union Mission in Somalia (Amisom) due to a dispute with the EU over the payment of wages.
Amisom salaries are paid by the EU but have not been received in Bujumbura for months as European diplomats seek to avoid sending money directly to a government against which the bloc imposed sanctions in response to a nearly two-year-long political crisis.
The EU wants to pay the salaries, worth $5.3m per month, directly to the troops.
But with no agreement yet made President Pierre Nkurunziza has instructed his foreign and defence ministers to begin the process of withdrawing Burundi's 5 400 soldiers, roughly one quarter of the Amisom total.
If the Burundian withdrawal goes ahead it could seriously weaken the ability of Amisom to fight the Shabaab, an al Qaeda-linked jihadist group committed to overthrowing Somalia's internationally-backed government.
"We have decided to begin the process, as we have long promised, because our troops engaged with Amisom cannot continue to work without being paid," said first vice-president Gaston Sindimwo.
Burundi's government threatened the withdrawal of its troops last month.
"We would like to continue supporting and securing Somalia, but we are obliged to put the withdrawal mechanisms in place," Sindimwo said, adding that Burundian soldiers have not been paid for 12 months.
Burundi has been in the throes of a serious, sometimes deadly political crisis since April 2015 when Nkurunziza announced his intention to run for a third term which opponents said was unconstitutional.
He went on to win an election in July that was boycotted by the opposition and criticised by outside observers.
Violence in Burundi has so far killed at least 500 people and driven more than 300 000 to leave the country.
The EU's decision to suspend payment of Burundian soldiers' salaries via Bujumbura is part of efforts to increase pressure on the government.
In March, the European Union - Burundi's largest donor - suspended direct aid to the regime.
The African Union, which is due to hold its next summit in Addis Ababa at the end of January, in November condemned the EU decision to suspend payment of Burundian soldiers' wages, warning of a potentially negative impact on the security situation in Somalia.