A second Royal Navy warship has been sent to the Mediterranean to help the fight against people smugglers.

Frigate HMS Richmond has arrived to join EU patrols off the coast of Libya.

The patrols are aimed at stopping human traffickers who offer to take refugees on a dangerous - and often fatal - journey to Europe.

HMS Enterprise is already gathering intelligence in the region but was needed to save almost 400 migrants last month after Italian authorities were overwhelmed.

Defence Secretary Michael Fallon vowed to "hit the traffickers hard".

A UN resolution means HMS Richmond's commanding officer will have powers to board and seize boats suspected to be involved in people smuggling.

Mr Fallon added: "These new powers are an important step forward. We will now be able to board the boats and detain the smugglers.

"Sending HMS Richmond to join HMS Enterprise in the Mediterranean shows Britain's determination to tackle this trade in human misery at source."

The announcement follows the landing of four migrant boats at an RAF air base in Cyprus on Wednesday.

Some 600,000 migrants have arrived in the EU by boat so far this year.

About 475,000 have landed in Greece and 137,000 in Italy, according to the International Organisation for Migration.

The body estimates that more than 2,000 people have died trying to make the crossing in 2015.

HMS Enterprise replaced HMS Bulwark, which saved 3,000 lives in the Mediterranean, in July.