Key talks to resolve the nuclear dispute between Iran and the world six major powers in addition to the European Union have started in the Iraqi capital Baghdad on Wednesday.

The meeting took place at one of the palaces in the presidential complex in the heavily fortified Green Zone in central Baghdad that houses the Iraqi government offices and some foreign embassies, including the U.S. embassy.

The last round of nuclear talks between Iran and the UN Security Council's five permanent members (the United States, Britain, France, Russia and China) plus Germany, known as P5+1, was held in Turkey's Istanbul in April, with all sides describing the talks as positive and agreeing to meet again in the Iraqi capital on May 23.

Wednesday's talks aim at pushing Iran to allow the International Atomic Energy Agency (IAEA) experts access to sites, people and documents the agency hopes to inspect to address concerns that the country might have been working on nuclear weapons.

For its part, Iraq hopes that hosting such a significant international meeting is another signal to the world after hosting the Arab League summit in late March, to confirm the country's emergence from isolation after wars and unrest.

The UN has by now imposed several rounds of sanctions against Tehran for its refusal to halt uranium enrichment, a technology that can be used to produce nuclear fuel or materials for bombs.

The EU, the United States and some other countries have imposed oil embargo as part of their sanctions to pressure Tehran into resuming talks on the country's nuclear program. They have also imposed tough banking sanctions aiming at limiting Iran's ability to sell oil, which accounts for 80 percent of its foreign revenues.