Iran has warned its next step in reducing commitments under the 2015 nuclear deal will be stronger, with a senior nuclear official saying that 20% uranium enrichment is an option.

Spokesman for Iran's Atomic Energy Organization Behrouz Kamalvandi said Monday Tehran has passed the 3.67% uranium enrichment cap set by a 2015 nuclear deal and reached about 4.5%.

"Twenty percent is not needed now, but if we want we will produce it. When we've put aside 3.67% enrichment we have no obstacle or problem with this action," Kamalvandi said.

Options for enriching at higher levels have been discussed with the Supreme National Security Council, the spokesman said.

"There is the 20% option and there are options even higher than that but each in its own place. Today if our country's needs are one thing, we won't pursue something else just to scare the other side a little more. But they know it's an upward trend," he said.

Kamalvandi said increasing the number of centrifuges is an option for Iran's third step in reducing its commitments to the nuclear deal, noting that restarting IR-2 and IR-2 M centrifuges is an option.

The remaining European signatories to the nuclear deal, he said, should act quickly to fulfill their promises because Iran will continue reducing its commitments to the deal until it achieves a result.

China blasts US 'bullying'

China said "unilateral bullying" by the United States was the cause behind Iran's measures.

"The facts show that unilateral bullying has already become a worsening tumor," said Chinese foreign ministry spokesman Geng Shuang at a press briefing in Beijing Monday.

The US withdrew from the nuclear deal in May 2018 and began reimposing sanctions on Iran in August 2018, targeting crucial sectors including oil exports and the banking system.

"The maximum pressure exerted by the US on Iran is the root cause of the Iranian nuclear crisis," Geng said.

The 2015 deal was reached between Iran and six world powers -- Britain, China, France, Germany, the United States and Russia -- and saw Tehran agree to drastically scale down its nuclear program in exchange for sanctions relief.

France, Germany and Britain -- the remaining Europeans partners of the international deal -- have urged Tehran to halt its advance towards higher enrichment and warned the country of unspecified consequences.

Iran warns Europeans against 'strange' actions

Foreign Ministry spokesman Abbas Mousavi warned European countries on Monday against any "strange" response to its move.

The diplomat noted that any action Iran takes next would be within the legal framework set by the JCPOA, "unless some countries want to take strange actions, in which case we will skip the third step and jump to the critical one.”

Asked if Tehran could withdraw entirely from the Joint Comprehensive Plan of Action (JCPOA), as the nuclear deal is called, Mousavi said "all the options" are possible but "no decision has been taken."

“We will take the third step in 60 days and are still weighing (our options), but if the remaining countries, particularly the Europeans, fail to honor their commitments…we will take the third step stronger,” Mousavi said.

On the possibility of reversing the decisions as the Europeans have demanded, Mousavi said Iran would only consider a reversal once the Europeans "meet our expectations and demands."

Commenting on Russia and China's position on recent developments, Mousavi said, “Iran has not pinned hope on any country, neither friendly ones such as Russia and China, nor the European countries. What is important is their commitment to their obligations under the deal.”

Iran will not play into the hands of others either, he asserted, arguing that the Islamic Republic "will decide independently on the basis of its national interests and security."

The Iranian official said any further negotiations on the JCPOA will only concern the implementation of its provisions and Tehran will not take part in talks for a new deal or changing the terms of the current agreement.

He said Iran does not "roll out a red carpet for the US, but its return to its [JCPOA] commitments will be a welcome step."

He described as “bizarre” a recent request by Washington for an emergency meeting of the International Atomic Energy Agency (IAEA) on Iran, saying if such a meeting is ever held Iran “will bring up all the broken promises” by the other sides.