Negotiations between Ethiopia, Egypt and Sudan over a multi-billion dollar dam on the Blue Nile will resume on Tuesday, nearly two months after Egypt left the talks, African Union chairperson Cyril Ramaphosa said on Monday.

A bitter dispute between the three countries over the filling and operation of the Grand Ethiopian Renaissance Dam (GERD) remains unresolved even after the reservoir behind the dam began filling in July.

"The resumption of the trilateral negotiations on the GERD ... is a reaffirmation of the confidence that the parties have in an African-led negotiations process," Ramaphosa, who is South Africa's president, said in a statement.

The resumption of talks comes two days after Ethiopia summoned the US ambassador over what it called an "incitement of war" between Ethiopia and Egypt by US President Donald Trump over the dam dispute.

Trump had called on Friday for an agreement between the countries, but said it was a dangerous situation and that Cairo could end up "blowing up that dam".

Egypt, which gets more than 90% of its scarce fresh water supply from the Nile and fears the dam could devastate its economy, left the negotiations in August after Ethiopia proposed a new timeline for filling the GERD.

Trump also said Ethiopia had broken a US-brokered agreement to resolve the dispute, forcing him to cut funds. The United States cut $100-million in aid to Ethiopia in September due to its position on GERD.

Ethiopian lawmakers said on Monday that "no force on earth" would stop the completion of the dam and that they were ready to defend it from internal as well as external attacks.

"We will defend any possible internal and external attacks and conspiracies and we shall complete the dam," the lawmakers from the lower House said in a statement.