The leaders of the Democratic Republic of Congo and Rwanda are set to sign a peace deal aimed at ending the long-running conflict in the region at a summit hosted by US President Donald Trump in Washington.

Ahead of the summit, there has been an escalation in fighting in resource-rich eastern DR Congo between government forces and rebels believed to be backed by Rwanda.

DR Congo's army accused its rivals of attempting to "sabotage" the peace process, but the M23 rebels said the army had launched an offensive in breach of a ceasefire.

At the start of the year, the M23 seized large parts of eastern DR Congo in an offensive that saw thousands killed and many more forced from their homes.

DR Congo's President Felix Tshisekedi and his Rwandan counterpart Paul Kagame have frequently exchanged insults in recent years, each accusing the other of starting the conflict.

Trump got the two countries' foreign ministers to sign a peace accord in June, hailing it as a "glorious triumph".

Tshisekedi and Kagame will now endorse it, with several other African and Arab leaders - including those of Burundi and Qatar - expected to attend the signing ceremony.

The M23 will not be present - it is in talks with DR Congo's government in a parallel peace process led by Qatar.

The Trump administration has spearheaded talks between DR Congo and Rwanda, hoping that resolving the differences between the two neighbours will pave the way for the US to increase investments in the resource-rich region.

Rwanda denies supporting the M23, despite UN experts saying its army is in "de facto control of M23 operations".

Despite the fanfare and the presence of the two leaders in Washington, some analysts are sceptical about whether the deal will lead to lasting peace.

A DR Congo researcher with the South Africa-based Institute for Security Studies think-tank, Bram Verelst, told the BBC that there was "currently no ceasefire in place, and the M23 rebellion continues to expand and consolidate its control".

"The signing ceremony is unlikely to alter this situation, though there is some small hope it could increase accountability on Congolese and Rwandan leaders to honour their commitments," he said.

The M23 seized key cities in eastern DR Congo earlier this year, including Goma and Bukavu.

In a statement, DR Congo army spokesman Gen Sylvain Ekenge said the rebels had launched a fresh offensive on Tuesday on villages in the South Kivu province.

The villages are about 75km (47 miles) from Uvira city, which lies on the border with Burundi, and has been the headquarters of the South Kivu regional government since the rebels seized Bukavu.

For its part, the M23 said the DR Congo army had launched an air and ground assault against its positions, and this was done in cahoots with Burundian forces.

Burundi has not commented on the allegation. It has several thousand troops in eastern DR Congo to support the embattled army.

Rwanda says it has adopted "defensive measures" in eastern DR Congo because of the threat posed by the FDLR militia group, which includes fighters who carried out the 1994 Rwandan genocide.

Kagame insists that the FDLR must be disarmed, while DR Congo demands the withdrawal of Rwandan troops from its territory.

Both of these conditions are included in the peace deal to be signed in Washington.

However, several deals going back to the 1990s have failed after Rwanda accused previous Congolese government of failing to disarm the FDLR, and this remains one of the main stumbling blocks in current efforts to end the conflict.

DR Congo's government has also demanded that the M23 gives up the territory it has seized, something it has so far refused to do in the Qatar-brokered talks.

Qatar and the US are co-ordinating their mediation efforts. Qatar has strong ties with Rwanda, while the US is seen to be closer to DR Congo.

The US State Department said in 2023 that DR Congo had an estimated $25trn (£21.2trn) in mineral reserves.

This includes cobalt, copper, lithium, manganese and tantalum - key ingredients needed to make the electronic components used in computers, electric vehicles, mobile phones, wind turbines and military hardware.

"We're getting, for the United States, a lot of the mineral rights from the Congo as part of it," Trump said, ahead of the deal signed in June.

Prof Jason Stearns, a Canada-based political scientist who specialises in the region, told the BBC that the US has been pushing for an economic agreement that could see DR Congo and Rwanda co-operate on hydro-electric power, mining and infrastructure development.

"The logic is that it will provide the peace dividend," he said.

However, DR Congo has made it clear that while it would sign the agreement, it would not "advance on that deal until Rwandan troops have withdrawn from eastern DR Congo", Prof Stearns added.