High-level officials are still meeting on the last day planned for negotiations on Iran’s nuclear program. The talks are taking place in the Austrian capital, Vienna.

Some observers believe a nuclear deal will be announced soon. But top diplomats involved in the talks have told reporters in the past 24 hours that important issues remain unresolved.

Iran is meeting with representatives of Britain, China, France, Germany, Russia and the United States. The foreign minister of the European Union has also been involved. Three other times, the negotiators failed to meet a time limit for reaching a nuclear agreement. Talks about limiting Iran’s nuclear activities have been taking place for more than 10 years.

A number of countries have limited trade with Iran to protest what they believe are its efforts to develop nuclear weapons. Iran has always denied that it is doing so. If a deal is reached, the economic restrictions could be cancelled.