PARIS - France demanded on Wednesday that Iran refrain from entering a new phase of "especially worrying" reductions to Iran's obligations to a 2015 nuclear deal with world powers.

"Iran must abstain from crossing an especially worrying new phase of new measures that could contribute to an escalation in tensions," French foreign ministry spokeswoman Agnès von der Muhll told reporters in a daily briefing.

She was responding after Iranian President Hassan Rouhani said on Monday that Tehran was working on advanced IR-9 centrifuges for uranium enrichment. Those centrifuges do not appear in the 2015 accord.

(Reporting by John Irish; Editing by Catherine Evans) ((sudip.kargupta@thomsonreuters.com; +33 1 49 49 53 84;))