Iran and the powers failed to meet a July 20 target date for an agreement and are due to hold their first negotiating round since then in New York on Sept. 18. The deadline for a deal has been extended to Nov. 24.
"My hope is that we will make progress. ... We believe although we are far apart, there is the possibility of being able to narrow the gap," Catherine Ashton told reporters in Ottawa when asked about her expectations for the New York round.
"But we are determined in so doing to do it fully aware that the world is watching and expecting that any agreement must be a good and positive one if it can be found."
Ashton was in Canada's capital, Ottawa, for a meeting with Foreign Minister John Baird.
The six powers - the United States, Russia, China, France, Germany and Britain - want Iran to scale back its nuclear program in exchange for phasing out tough sanctions.
Western countries suspect Tehran wants to be able to build a nuclear bomb. Iran says it is a peaceful project to generate electricity. REUTERS