Senior diplomats from Iran and major powers met online Wednesday to discuss the state of their nuclear deal that is eroding despite conciliatory signals from U.S. President-elect Joe Biden.

The consultations are meant to prepare for upcoming talks among foreign ministers from Iran, Britain, France, Germany, Russia and China, according to diplomats.

Iran has far more enriched uranium than allowed under the agreement that was reached in 2015, and has plans to install advanced equipment that could speed up this process, the International Atomic Energy Agency (IAEA) in Vienna said in two recent reports. The nuclear deal is meant to prevent Iran from amassing uranium that could be used for nuclear weapons. In return, major powers promised to end Iran's economic isolation by lifting sanctions.

U.S. President Donald Trump pulled out of the pact and revived U.S. sanctions in 2018. One year later, Iran started abandoning key provisions of the deal. Iran's pragmatic President Hassan Rouhani and his future U.S. counterpart Biden have both said they are willing to return to the agreement. However, Iranian hardline parliamentarians pushed through a law earlier in December that would allow the government to ramp up uranium enrichment and block IAEA inspectors, as reported by Deutsche Presse-Agentur (dpa).

Wednesday's talks were also overshadowed by the assassination of a high-ranking Iranian nuclear physicist in late November. Foreign Minister Mohammad Javad Zarif has put the blame on Israel, which is opposed to the nuclear deal. Iran's execution of a dissident journalist Saturday further soured the diplomatic atmosphere.

Before the start of Wednesday's talks, Russia's ambassador to international organizations in Vienna, Mikhail Ulyanov, tweeted that the focus would be on how to "preserve the nuclear deal and ensure its full and balanced implementation," adding that the "role of (the) U.S. in this regard will inevitably be discussed."

According to Agence France-Presse (AFP), another diplomat said the meeting would rather be "an opportunity to say to the Iranians face to face to stop the breaches of the deal" and not to ruin the chances of a return to diplomacy under Biden. The meeting "is not coming at the best moment," the diplomat admitted, given the uncertainty over possible developments between now and Biden's Jan. 20 inauguration.

On Monday, European Union foreign policy chief Josep Borrell said Wednesday's meeting was part of "our work in order to keep the (Joint Comprehensive Plan of Action) JCPOA alive." A few days earlier he had emphasized that the deal was "the only way to avoid Iran becoming a nuclear power" and said a meeting of ministers from participants in the JCPOA would be called before Christmas.