"We call on Iran to enter, without preconditions, into a sustained process of serious dialogue, which will produce concrete results," the United States, China, Russia, France, Britain and Germany, known as the P5+1, or Iran Six said in a statement.

The group also expressed hope that the upcoming talks would contain “serious discussions on concrete confidence building measures."

Iran’s Parliament Speaker Ali Larijani warned on Wednesday that future negotiations between Tehran and the P5+1 would be fruitless if the West continued to pressure the Islamic Republic.

Iran and the P5+1 have already held two rounds of talks, one in Geneva in December 2010 and another in Istanbul, Turkey in January 2011.

The Iran Six has been trying to convince Iran to halt its uranium enrichment program and to alleviate concerns about its nuclear ambitions since 2003.

Iran is already the subject of a wide range of international sanctions because the West, led by the United States, accuses Tehran of pursuing a secret nuclear weapons program. However, the Islamic Republic insists its nuclear power needs are for civilian purposes only.