US president tells Paul Kagame that backing rebel group in eastern Congo is 'inconsistent with desire for stability and peace'

Barack Obama has urged the Rwandan president, Paul Kagame, to halt support for rebels in eastern Democratic Republic of the Congo, a move welcomed by critics of Kagame's government.

The United States, and in particular its UN ambassador, Susan Rice, have been accused of turning a blind eye to Rwanda's meddling in its neighbour, partly because of residual guilt over the 1994 genocide.

But in a phone call to Kagame, Obama "underscored that any support to the rebel group M23 is inconsistent with Rwanda's desire for stability and peace".

The White House said the US president stressed "the importance of permanently ending all support to armed groups in the DRC, abiding by the recent commitments he made… and reaching a transparent and credible political agreement that includes an end to impunity for M23 commanders and others" who committed rights abuses.

Obama "welcomed President Kagame's commitment to moving forward in finding a peaceful solution" in eastern Congo, it added.

A recent UN report presented detailed evidence that the Rwandan government is backing the rebels, a charge that Kagame's government has repeatedly denied. M23 members have allegedly perpetrated rapes, recruited child soldiers and carried out summary executions in eastern Congo.

America has been criticised for a muted response. Rice, who is close to Kagame, delayed the UN report's publication for weeks and prevented a security council resolution from explicitly naming Rwanda as a supporter of M23.

While Britain and others have suspended financial support to Rwanda, the US cut only $200,000 (£128,000) of military aid from a programme worth around $200m. Last week 15 leading campaign groups and thinktanks wrote to Obama accusing him of a failed policy and called for the president to impose sanctions.

His intervention has been hailed as potentially signalling a new, tougher approach. "It's good news for us," said Jean-Baptiste Ryumugabe of the Rwandan opposition Social Party Imberakuri. "We hope Paul Kagame will listen to President Obama because up to now many presidents and many organisations have asked him to stop fuelling the rebel group in eastern Congo but he refused. We have to hope he will now react positively."

Ryumugabe called for the US to take further measures such as cutting financial aid and limiting visas for travel to the US. "They have many things they can do to stop this aggression," he said.

Other Rwandan opposition groups said they were "greatly encouraged" by Obama's remarks. "It is absolutely important that the United States has taken this important and crucial step in seeking to bring president Paul Kagame to account for his actions in the Democratic Republic of Congo," said a letter addressed to Obama by the Rwanda National Congress and FDU-Inkingi.

"Your voice and effort to bring Rwandan leaders of the M23 rebellion to account will be instrumental in stopping and reversing the carnage in DRC."

But some questioned why Obama did not speak out sooner. Carina Tertsakian, senior researcher on Rwanda for Human Rights Watch, said: "They've lagged behind in terms of coming out strongly to denounce Rwandan support for M23. They've been unforthcoming.

"Obama's words come quite late given how far the situation in eastern DRC has deteriorated in recent months, but we welcome talks at such a high level."

In a further sign that US patience is wearing thin, the treasury department has imposed sanctions against two leaders of M23, Baudoin Ngaruye and Innocent Kaina, who are accused of using child soldiers. Ngaruye was cited for targeting children through "killing, maiming, and sexual violence".

The move comes just weeks after a UN security council sanctions committee added the two men to its consolidated travel ban and asset-freeze list.

Tertsakian urged the US to impose sanctions on senior Rwandan officials, including the defence minister and army chief of staff, because of their links to the rebellion in Congo.

The US has launched a fresh appeal for the arrest and prosecution of Sylvestre Mudacumura, the head of Rwanda's main Hutu rebel group, and Congo's Bosco Ntaganda, an ex-general who spurred the ongoing mutiny in the east. Both are the subject of outstanding international criminal court warrants.

M23 seized the strategic town of Goma in eastern Congo on 20 November as Congolese troops retreated to the nearby town of Minova. An investigation by the UN has found at least two deaths and 126 cases of rape in and around Minova in the 10 days that followed. Nine Congolese army soldiers have been arrested.