US warns Iran over alleged support of Yemeni rebels

US Secretary of State John Kerry has warned Iran not to provide support to Houthi rebels in Iran, insisting that the US would support any state in the Middle East that felt threatened by Tehran.

"There are obviously supplies that have been coming from Iran,” Kerry told PBS NewsHour. “There are a number of flights every single week that have been flying in.

"Iran needs to recognise that the US is not going to stand by while the region is destabilised or while people engage in overt warfare across lines, international boundaries and other countries.”

Iran has denied that it is providing military aid to the Houthi, but it dispatched two warships to the Gulf of Aden, off the southern coast of Yemen, on Wednesday.

Iranian navy commander Rear Adm Habibollah Sayyari said that Tehran deployed these ships as a means of "safeguarding naval routes for vessels in the region".

The United States is supporting a Saudi-led coalition to drive back the rebels and restore President Abdrabbuh Mansour Hadi, who fled the country last month.

Fighting in the city of Aden between the Houthis and Hadi-loyalists has intensified, and at least 22 people were reportedly killed on Wednesday.

Aid groups have described conditions for civilians as catastrophic.

Iran has proposed a four-step solution to ending the crisis, involving a ceasefire, delivery of humanitarian aid, national dialogue and the formation of a broad-based government.

A ship carrying 1.7 tonnes of medical aid for Medecins Sans Frontieres and another International Committee of the Red Cross (ICRC) boat carrying medical supplies and staff, docked at the port city.

The World Health Organization has estimated that at least 560 people, including 76 children, have been killed in Yemen between 19 March and 4 April. A further 1,700 people were wounded and 100,000 have fled their homes.