Beijing is a close partner of Iran and has urged the United States and Israel to cease their attacks on the country, while also criticising Tehran's strikes against Gulf states housing US military bases.

China's foreign ministry spokesman Lin Jian said the war had caused "grave humanitarian catastrophes" in Iran and other Middle Eastern nations.

"China has decided to provide emergency humanitarian assistance to Iran, Jordan, Lebanon and Iraq. It is hoped this will help alleviate the humanitarian plight faced by the local populations," Lin told a press conference, without providing further details.

"China will continue to make every effort to promote peace and stop the war... and to prevent further spreading of the humanitarian crisis," he added.

China has sought to mediate in the war, with its special envoy to the Middle East, Zhai Jun, urging de-escalation when he recently met Saudi Arabia's foreign minister for talks.

China's top diplomat, Wang Yi, has also said that the war "should never have happened" and called for an end to fighting.

The humanitarian aid announcement came after US President Donald Trump said he would delay a planned visit to Beijing.

Trump, who postponed his planned visit to Beijing due to the war, according to the White House, has also pressured China to help Washington reopen th Strait of Hormuz.

The vital sea passage, through which a fifth of global oil supplies normally pass, was effectively closed by Iran in retaliation to US and Israeli strikes.