China's representative at talks on Iran's nuclear program said on Thursday he saw hope that a deal would be done, a day after US Secretary of State John Kerry said "significant gaps" remained to be negotiated."We are at the final stage of our efforts for a comprehensive agreement," Wang Qun, Director-General of the arms control department of China's Foreign Ministry, told reporters."We do think that it's a last stage and hopefully we could reach an agreement."Wang was speaking in Montreux, the Swiss lakeside town where Kerry and Iranian Foreign Minister Mohammad Javad Zarif wrapped up 10 hours of talks over three days on Wednesday.Kerry flew on to Riyadh, where he briefed Gulf Arab leaders on Thursday, leaving senior diplomats from Iran and the so-called P5+1 countries - the United States, China, Russia, France Britain and Germany - to continue negotiations.The six powers and Iran have set an end-June deadline to reach an agreement that curbs sensitive Iranian nuclear work in exchange for sanctions relief. The Western powers hope to have a political framework agreement by the end of March."Basically there are two categories of issues," Wang said in English. "One is how to see the non-proliferation concern is removed and secondly is to see the Iranian rights for peaceful uses (of nuclear technology) is ensured."Zarif said in a US television interview on Wednesday that he was prepared to work round the clock for a deal."We believe that we are very close, very close and we could be very far," Zarif said.