WASHINGTON (Reuters) - Syrian opposition groups should seize the historic opportunity to attend peace talks in Geneva planned for Friday and go without preconditions, the U.S. State Department said on Wednesday.

“Factions of the opposition have an historic opportunity to go to Geneva and propose serious, practical ways to implement a ceasefire, humanitarian access and other confidence-building measures, and they should do so without preconditions,” State Department spokesman Mark Toner said.

“We believe it should seize this opportunity to test the regime’s willingness and intentions, and expose before the entire world which parties are serious about a potential peaceful political transfer in Syria, and which are not,” he told a briefing.

Opposition groups adjourned a meeting in Saudi Arabia on Wednesday saying they were waiting for a U.N. response to their demands.

Preparations for the talks, already postponed from Monday to Friday, have been beset by problems, including a dispute over who should represent the opposition.

“The Syrian people are looking to this process and they need signs of hope that they are not destined to live in conflict indefinitely,” Toner said. He added: “There is an urgency to getting these talks started.”