During negotiations with the US, Iran is trying to achieve a significant easing of sanctions and the return of its frozen assets, amounting to about $20 billion, a source familiar with the negotiations said, CNN reports.

According to the source, Tehran also demands an expansion of the scope of economic privileges as a step towards normalizing relations with Washington.

The parties are discussing the possibility of a comprehensive agreement, but fundamental differences do not yet allow for a final result.

Earlier, information was disseminated about a number of contacts between the US and Iran, but the exact dates for the next round of consultations have not yet been determined.