Iran accused Israel on Wednesday of “trumpeting lies to poison” the nuclear talks going on in Vienna with world powers meant to reach a deal regarding Iran’s nuclear program.

“Israeli regime whose existence relies on tension is at it again, trumpeting lies to poison Vienna talks,” tweeted Iranian Foreign Ministry spokesman Saeed Khatibzadeh.

“All parties in the room now face a test of their independence & political will to carry out the job—irrespective of the fake news designed to destroy prospects for success,” he posted.

Meanwhile, on Wednesday, Tehran started producing enriched uranium with advanced centrifuges at the Fordow plant, according to the International Atomic Energy Agency, as reported by Reuters.

European diplomats said on Tuesday that if Iran does not demonstrate seriousness in nuclear negotiations with world powers this week, it will be a sign of immediate problems to come.