US President Barack Obama on Wednesday (14 December) refused to sign a bill renewing sanctions against Iran but decided to let it become law without his signature, Josh Earnest, White House Press Secretary said.

"This administration has made clear that an extension of the Iran Sanctions Act, while unnecessary, is entirely consistent with our commitments in the Joint Comprehensive Plan of Action (JCPOA)," Earnest said referring to the acronym for the nuclear deal.

The White House had previously said that Obama would sign the renewal.

After a bill is passed by Congress, a president can either sign it, veto it or take no action in 10-days, according to the constitution.

If Congress is in session, the bill becomes law with no signature. If Congress is adjourned, the failure to sign the bill becomes "pocket veto" and stops the bill from becoming the law, Associated Press reported. Congress is technically still in session and is holding "pro-forma" sessions even if many legislators have gone back home for the holidays.

US lawmakers insisted that the renewal of the sanctions was important to keep up pressure on Iran to abide by the deal and keep a check on its behaviour in the region. The Obama administration said that the renewal will not affect Iran as long as it honours the nuclear deal.

Secretary of State John Kerry said in a statement "Extension of the Iran Sanctions Act does not affect in any way the scope of the sanctions relief Iran is receiving under the deal or the ability of companies to do business in Iran consistent with the JCPOA."

According to AP, the latest development was a symbolic attempt by the President Obama to disapprove the actions of the legislators.

Iran had pledged to give an answer if sanctions were renewed and said that they violate the nuclear deal between Iran and the world powers (US, China, Russia, the UK, France and Germany).