The U.S. special envoy for Sudan is seeking "tangible results" from talks to end the devastating war, despite the Sudanese government's absence.

War has raged since April 2023 between the Sudanese army under the country's de facto ruler Abdel Fattah al-Burhan and the paramilitary Rapid Support Forces (RSF), led by his former deputy Mohamed Hamdan Daglo.

The RSF delegation is taking part in the U.S.-brokered talks on securing a cease-fire which began at an undisclosed location in Switzerland on Wednesday.

However, the Sudanese armed forces (SAF) are unhappy with the format arranged by Washington and are not participating.

U.S. special envoy for Sudan Tom Perriello said on X that the second day of the talks was underway.

"We continue our relentless work with international partners to save lives and ensure we achieve tangible results," he said.

At the end of the first day, the United States again urged Sudan's army to join the talks, which are taking place behind closed doors and could last up to 10 days.

Sudan again made its opposition clear on Thursday.

"It is the nature of Sudanese people to reject threats and intimidation," Finance Minister Gibril Ibrahim wrote on X.

"Their government, of the same ilk, will not accept mediation imposed by force, and will not be a party to negotiations aimed at legalizing the criminal militia's occupation of civilian facilities and preserving its place in the political and security scene in the future," he said.

The talks are co-hosted by Saudi Arabia and Switzerland, with the African Union, Egypt, the United Arab Emirates and the United Nations acting as a steering group.

The Sudanese army has repeatedly accused the UAE of backing the RSF – allegations the UAE denies.

Previous talks in the Saudi city of Jeddah came to nothing.

The talks in Switzerland aim to agree a cease-fire, improve humanitarian access and set up enforcement mechanisms.

The brutal conflict has triggered one of the world's worst humanitarian crises.

More than half of the population faces acute hunger while fighting has forced one in five people to flee their homes and tens of thousands have died.