Burundi army
Soldiers patrol the streets as civilians celebrate in Burundi's capital Bujumbura, after the coup was announced on Wednesday 13 May 2015Reuters

Soldiers backing the coup d'etat in Burundi's capital are anticipating the arrival of reinforcements as three military units made their way to Bujumbura, a source close to the Ministry of Defence told IBTimes UK.

Maj Gen Godefroid Niyombare on Wednesday (13 May) announced that the army was taking over the country in a coup d'etat, as President Pierre Nkurunziza was travelling to Tanzania where he was supposed to meet East African leaders to discuss the violence in Burundi.

The factions of the country's armed forces that back Nkurunziza, led by Army Chief of Staff Gen Prime Niyongabo, were this morning said to be in control of key positions such as the presidential palace and main radio station RTNB.

However, IBTimes UK understands the army reinforcements are expected to join the soldiers backing the coup d'etat who have been planning to re-take "by force" the two state institutions.

Three military units called in to help

The Mwaro and Ngozi units are on their way to the capital, while troops from Muyinga province have already entered the capital, sources close to the Ministry of Defence said on Thursday (14 May) morning.

"The military unit from Musaga has already arrived to support the putschists in Bujumbura," Pierre-Claver Mbonimpa, the leader of Burundi's civil society and opposition figure, confirmed in a phone interview with IBTimes UK from Bujumbura.

Another source confirmed Mwaro and Muyinga troops, who control much of the army's weaponry, are on their way.

According to the source, troops from Ngozi, "the president's province", are expected to arrive later Thursday.

While the president was born in the capital Bujumbura, he grew up and was educated in Ngozi province, where he built two "European-style" football stadiums.

UPDATE:

(11:57 GMT 14 May): Mwaro troops have already joined the armed forces backing the coup, and have been using their armoured vehicles to attack the state broadcaster RTNB, which was still in the bands of loyalists.

Muyinga, Kayanza and Cibitoke troops have also arrived in Bujumbura.

According to a source close to the Ministry of Defense, much of the Ngozi unit went back to Ngozi where it is allegedly taking control of the President's home in the province, but IBTimes UK can not confirm this as of yet.

(11:15 GMT 14 May): Witnesses confirm heavy fighting and shelling can be heard near the state-run national broadcaster RNTB in Burundi's capital, Bujumbura.

A witness, hiding some 800 metres away from the building, told IBTimes UK the shots fired came from "heavy weapons" - supposedly armoured vehicles.

"We can hear very loud shelling from tanks. They (army tanks) have surrounded the building," Pierre-Claver Mbonimpa, the leader of Burundi's civil society and opposition figure, confirmed in a phone interview with IBTimes UK from Bujumbura.

Who is loyalist? Who is backing the coup?

While the situation is still very unclear, sources have told IBTimes UK a divided army has taken different stands in this conflict.

Backing the coup:

- Burundian Parachute Battalion, the "beret rouges" (red berets)

- Burundi's 11th Tank Battalion, known as the "bérets noirs" (the black berets)

- ISCAM, the Reserve Officers School

- 'BASE' unit based nearby Musaga, which provides equipment for the army

Backing the President:

- Police forces

- Imbonerakure militias, who are reported to have joined the police

- Garde Presidentielle: personal guards and elements of the presidential guard. Said to be important, both in number and equipment