British Prime Minister Boris Johnson warned Iran on Tuesday that time was running out to salvage a 2015 nuclear accord with major powers.

In a call with Israeli Prime Minister Naftali Bennett, Johnson discussed the ongoing talks on the Iran nuclear deal in Vienna.

"The prime minister said the UK wants to see the negotiations in Vienna lead to full restoration of the JCPOA, but that we need Iran to engage in good faith," a Downing Street spokesman said. "The diplomatic door is open, but time is running out to reach an agreement."

European participants in the talks, the UK, France and Germany have been warning Iran that the talks cannot drag on.

Iran interrupted the Vienna negotiations to restore the JCPOA in June for five months and returned to talks in late November. Diplomats say so far, some limited progress has been made but major issues remain to be solved.

In the meantime, Iran continues high-level uranium enrichment, deepening concerns that it might be aiming to build more leverage as it gets closer to building a nuclear bomb.

Talks continue in Vienna with different delegations holding bilateral and multilateral discussions. Iran’s chief negotiator Ali Bagheri-Kani Tuesday met with Russia’s envoy Mikhail Ulyanov, but the contents of the talks have not been disclosed.

With reporting by Reuters