"The UK is permitted under international law to use force in such circumstances where acting in self-defence is the only feasible means to deal with an actual or imminent armed attack and where the force used is necessary and proportionate," the document said.

The document was titled 'Summary of the UK Government Legal Position: The legality of UK military action to target Houthi facilities in Yemen' and was published on the government website.

The British government will notify the United Nations Security Council of the actions it has taken, it added.

Earlier, Russia said the attack on Yemen took place without any mandate from the United Nations and was thus an illegal "adventure" by the United States and its allies.

(Reporting by William James and Muvija M, Editing by Kylie MacLellan)