Democratic Republic of Congo (DRC) and Rwanda have vowed to come up with a draft peace deal by May 2 and refrain from providing military support to armed groups, according to an agreement signed in Washington on Friday as part of diplomatic efforts to end violence in eastern Congo.

Two days after Qatar mediated a surprise truce, the United States brought the two countries' foreign ministers together on Friday and voiced an interest in investment in the DRC's turbulent but mineral-rich east.

The agreement, reached amid an unprecedented advance by Rwandan-backed M23 rebels in Congo, is expected to bring "significant" US public and private investment to the region, which is rich in minerals including tantalum and gold, the final text said.

The deal raises hopes that the latest cycle of violence in a decades-long conflict rooted in the Rwandan genocide might ease, with both countries hoping to attract significant US investments in minerals. However, previous ceasefire calls have not produced a sustained break in the fighting.

Both parties also agreed to look into a joint security coordination mechanism to crack down on armed groups and criminal organisations.

Foreign ministers from the two countries signed the agreement at a ceremony with US Secretary of State Marco Rubio, who also signed as a witness.