After a brief interruption, negotiations to save the nuclear deal with Iran are set to continue in Vienna on Tuesday.
The coming weeks are considered crucial for the possible restoration of the arms control agreement from 2015.
Western diplomats say Iran is making great strides towards the capability to produce a nuclear bomb and that it is therefore increasingly urgent to reach an effective agreement that would again limit Iran’s nuclear capabilities to purely civilian applications.
Germany, France and Britain, together with Russia and China, have been mediating between Iran and the United States for months.
The aim is to lift U.S. economic sanctions and, in return, to restrict Iran’s nuclear programme again.
Under former president Donald Trump, the U.S. unilaterally withdrew from the agreement. Tehran then violated the conditions of the agreement, including by enriching uranium to a level that is no longer far from a weapons capability.