The US government on Thursday slapped sanctions on two militant groups accused of "fomenting violence and instability" in the eastern part of the Democratic Republic of Congo (DRC).

The Department of Treasury blacklisted Mouvement du 23 Mars ( M23) and the Forces Democratiques de Liberation du Rwanda (FDLR), alleging that as armed groups operating in eastern DRC, they have committed "serious crimes" involving the targeting of children in the conflict in the African country.

"These crimes, which include recruitment as well as killing, maiming and sexual violence, violate international law and are the basis for the groups' designation today," the Treasury said in a statement.

M23 was targeted also for receiving arms and material related to military activities that have contributed directly to the ongoing conflict, the agency said.

The M23 rebellion started in April last year, when a militia that had been integrated into the DRC armed forces mutinied. The militant group has since taken control of large parts of eastern DRC, which is rich in mineral resources, and captured Goma, the capital of the North Kivu province, in November but withdrew soon to start negotiations with the government.

The FDLR is led by Rwandan Hutus who were involved in the 1994 Rwandan genocide, the Treasury said, noting that top commanders of both groups, M23's Bosco Ntaganda and FDLR's Sylvestre Mudacumura, are wanted by the International Criminal Court.

"Both groups have been actively recruiting and using children in armed conflict," the agency said. "They have been responsible for campaigns of horrific violence against the civilian population in the DRC, and they have used their resources to undermine peace efforts in the region."

"The United States is committed to working with the international community to end the violence perpetrated against children in the DRC and exposing those responsible for these atrocities," David Cohen, under secretary of Treasury for terrorism and financial intelligence, was quoted as saying.

"We also urge Rwanda to halt its assistance to M23 and prevent any and all forms of support to Congolese armed groups," he added.

The UN Security Council DRC Sanctions Committee added M23 and the FDLR to its consolidated travel ban and asset freeze list late last month, while the Security Council and the US government have imposed sanctions on several leaders of the two groups.