TEHRAN (Tasnim) - China on Wednesday defended the World Health Organization and lashed out at the US decision to withdraw from the UN body.

Foreign ministry spokesperson Zhao Lijian said the move was "another demonstration of the US pursuing unilateralism, withdrawing from groups and breaking contracts."

WHO is "the most authoritative and professional international institution in the field of global public health security," Zhao said at a daily briefing, AP reported.

The US departure from the organization "undermines the international anti-epidemic efforts, and in particular has a serious negative impact on developing countries in urgent need of international support," Zhao said.

The Trump administration formally notified the UN on Monday of its withdrawal from WHO, although the pullout won't take effect until next year. That means it could be reversed by a new administration or if circumstances change.

Former Vice President Joe Biden, the presumptive Democratic presidential nominee, said he would reverse the decision on his first day in office if elected.

US President Donald Trump has harshly criticized WHO over its response to the coronavirus pandemic and accused it of bowing to Chinese influence. Trump said in a White House announcement that Chinese officials "ignored" their reporting obligations to WHO and pressured the organization to mislead the public about an outbreak that has now killed more than 130,000 Americans.

The move was immediately assailed by health officials and critics of the administration, including numerous Democrats who said it would cost the US influence in the global arena while undermining an important institution that is leading vaccine development efforts and drug trials to address the coronavirus.

The withdrawal notice was sent to UN Secretary-General Antonio Guterres on Monday and will take effect in a year, on July 6, 2021.

The US is WHO's largest donor and provides it with more than $450 million per year, but owes about $200 million in current and past dues. Those financial obligations must be met before a US withdrawal can be finalized.