Iran has reiterated its call for the removal of all sanctions before a final nuclear deal with the P5+1 group as the country wraps up another round of nuclear talks with six world powers.

"Our principle position is that all sanctions are lifted at once," Iran's senior nuclear negotiator, Abbas Araqchi, said on Thursday following his talks with officials from the P5+1 group in the city of Montreux, Switzerland, Press TV reported.

Araqchi, who is also deputy foreign minister for legal and international affairs, stressed that an agreement could be achieved with the world powers "only if sanctions are lifted."

Noting that the lifting of the sanctions was a "very important aspect" in the negotiations, he added, "No sanctions should be remained in place."

The Iranian diplomat called on the world powers to decide between achieving a "deal" and continuing to "pressure" Iran through sanctions.

He said Iran and the world powers are trying their best to reach a sort of "understanding" by the end of the month, noting that "major issues" still remain to be resolved.

His remarks came after representatives of Iran and the P5+1 group of countries wrapped up deputy-level negotiations over Tehran's nuclear programme in the city of Montreux, Switzerland.

Earlier on Thursday, deputy foreign ministers of Iran and the six world powers sat down for talks in the Swiss city.

Later in the day, Iranian Deputy Foreign Ministers Seyyed Abbas Araqchi and Majid Takht-e-Ravanchi met with their Russian and Chinese counterparts, Sergei Ryabkov and Wang Qun, in Montreux.

On Wednesday, Iran's negotiators held quadrilateral deputy-level talks with Hans Dieter Lucas from Germany, Simon Gass from Britain and Nicolas de Riviere from France.

On the same day, Iran's Foreign Minister Mohammad Javad Zarif and his American counterpart, John Kerry, wrapped up intense negotiations in Montreux. Head of the Atomic Energy Organisation of Iran (AEOI) Ali Akbar Salehi and US Energy Secretary Ernest Moniz also attended the talks.

Iran and the P5+1 countries -- Russia, China, Britain, France, the US plus Germany -- are seeking to seal a comprehensive nuclear deal by July 1.

The two sides have already missed two self-imposed deadlines for inking a final agreement since they signed an interim one in the Swiss city of Geneva November 2013.