The battle for control in Democratic Republic of the Congo (DRC) is coming to a head as the country prepares for presidential elections. Eastern regions of the DRC are still at the mercy of armed groups and the Congolese armed forces, who have all been accused of committing serious abuses against civilians.

The rebel M23 group was defeated in eastern DRC in late 2013, after a 20-month campaign led by the Congolese army and backed by thousands of UN fighters, but civilians are still living in fear of sexual violence, kidnappings and killings. Conflict rages over control of land, mineral resources, and ethnic division.

Significant obstacles to the nation's transition to stability and democracy still remain in the form of more than 50 different armed groups operating in DRC's eastern borderlands.

"While some have a few thousands of combatants (such as the FDLR) and highly sophisticated structures of command, including supply and training, others are 10 or 20 people rag-tag gangs whose composition can change on a weekly basis," according to political analyst Christoph Vogel.

In this series, IBTimes UK takes a closer look at the armed groups fighting in the eastern regions of South and North Kivu.

Battle for control of the DRC

Check out our Flipboard magazine - Who's who in the battle for DRC by IBTimes UK

Democratic Forces for the Liberation of Rwanda (FDLR)

FDLR has been one of the most abusive armed groups in eastern Congo over the past two decades.

Allied Democratic Forces (ADF/NALU)

Allied Democratic Forces (ADF), a Ugandan-led Islamist armed group, is one of the oldest in DRC.

Mai-Mai groups

Mai-Mai groups are the most prolific recruiters of child soldiers and perpetrators of human rights abuses.

Nyatura rebels

Nyatura, a Congolese Hutu militia, collaborated with FDLR rebels and the Congolese army to defeat M23.

National Congress for the Defence of the People (CNDP)

In 2009 the CNDP became a political party and 3,000 - 4,000 of its fighters joined the Congolese army.

Lord's Resistance Army (LRA)

Joseph Kony took over as leader of the Holy Spirit Movement and re-branded it as the Lord's Resistance Army.

Raia Mutomboki

Raia Mutomboki started operating in 2011 for self-defence against attacks perpetrated by the FDLR.

Front for Patriotic Resistance in Ituri (FRPI)

FRPI have been an active armed militia and political party in DRC's north-eastern region of Ituri.

Patriotic Forces for the Liberation of Congo (FPLC)

FPLC was involved in human rights violations including ethnic killings, torture, rape, and mutilation.

Armed forces of the DRC (FARDC)

After the Second Congo War came a new unified national army supposed to integrate various armed groups.

Enyelle and Independent Movement of Liberation and Allies (MILIA)?

After attacking Dongo MILIA carried out targeted killings against the Boba before moving southwards.

DRC armed groups M23
A soldier from the March 23 Movement (M23) rebel group, also known as the Congolese Revolutionary Army, wearing a belt of ammunition, walks down a street in Goma in the eastern Democratic Republic of Congo (DRC). REUTERS/James Akena