<span style="color: #222222;">China has called on all parties to uphold the Iranian nuclear pact after Tehran said it would end curbs on its uranium enrichment stockpile unless other powers helped it bypass renewed US sanctions. </span><br />'' <br />'' <span style="color: #222222;">Chinese foreign ministry spokesman Geng Shuang at a regular press briefing today said maintaining and implementing the comprehensive agreement is the shared responsibility of all parties. </span><br />'' <br />'' <span style="color: #222222;">Tehran has warned that if the five other parties to the agreement — China, Britain, France, Germany and Russia — failed to deliver on their commitments within 60 days to help Iran benefit from the deal despite the US sanctions, it would suspend other key limits set by the deal. </span><br />'' <br />'' <span style="color: #222222;">Iran's announcement that it would stop respecting limits on its nuclear activities is in response to sweeping unilateral sanctions reimposed by Washington.</span><br />''