GENEVA (Reuters) - The United Nations Special Envoy for Syria said after meeting representatives of the United States, Russia and other major powers on Wednesday that Syria peace talks were still planned to start in Geneva on Jan. 25.

United Nations (U.N.) Special Envoy for Syria Staffan de Mistura attends a meeting on Syria with representatives of the five permanent members of the Security Council (P5) at the United Nations European headquarters in Geneva, Switzerland, January 13, 2016. REUTERS/Denis Balibouse

Staffan de Mistura told reporters they had discussed access to the government-besieged town of Madaya, where the first aid deliveries were made on Monday to starving civilians after three months.

“This meeting was essential in order to move forward on the Geneva talks, and there are issues still, and very much at stake, that’s why I needed to consult them,” he said.

Assistant U.S. Secretary of State Anne Patterson said the talks were still “on track” for Jan. 25 and she had had a “good conversation” with Russian Deputy Foreign Minister Gennady Gatilov and senior officials from Britain, China and France.

“Everyone’s primary concern is humanitarian access given some of the dire situations that are taking place inside of Syria,” Patterson told reporters.

Syrian rebel groups said earlier on Wednesday they would not take part in the peace talks unless humanitarian articles in the latest U.N. resolution on the conflict were implemented.

The groups, who include the powerful Islam Army, mentioned articles 12 and 13 of a resolution passed late last year, which calls for humanitarian access to all in need and the cessation of attacks on civilians.

De Mistura’s office issued a statement saying that officials from the five permanent members of the U.N. Security Council had agreed to push for “sustained and unimpeded access to a number of besieged areas” in Syria’s civil war.

“The Special Envoy and his team will continue working hard to issue the invitations in order to ensure maximum inclusivity, with a view to starting the intra-Syrian Geneva Talks on 25 January,” it said.

The opposition council told de Mistura that the Damascus government would have to take goodwill steps, including a prisoner release, before they would go to negotiations.

Russia’s Foreign Ministry said on Twitter that Gatilov would meet representatives of various opposition groups on Thursday. It also said the international powers needed to do more work to agree lists of groups to be regarded as terrorists.

Patterson said the United States and Russia were working “very assiduously” on the question of defining terrorist groups. They had been discussing “the terrorism issue in the whole Syria-Iraq corridor” for months, and military and intelligence contacts were continuing.