Green activists wearing gas-masks have been protesting at US cruiseship Carnival Corp's AGM in London on Tuesday morning.

Environmental group Stand.earth said the action at the Mandarin Oriental hotel in Hyde Park was aimed at shareholders.

It said their "sombre message" is that "Carnival pollutes" and urged the shipowner to switch to cleaner fuel.

Inside the AGM, retired mechanical engineer and former ministry of defence naval scientist Ralph Hardwick intervened to ask company bosses a question.