Ships sailing under a British flag will be able to carry armed guards to protect them from pirates, the prime minister has announced.
David Cameron says he wants to combat the risks to shipping off the coast of Somalia, where 49 of the world's 53 hijackings last year took place.
No ship carrying armed security has yet been hijacked, the government claims.
However, allowing ships to carry armed guards may fall foul of（与……冲突） laws in other countries, such as South Africa.
Many British-registered ships already illegally carry armed guards because companies feel they have no alternative.
Shoot to kill?
Mr Cameron revealed he wanted to make the practice legal after talks in Australia with Commonwealth leaders from the region over the escalating problem faced in waters off their shores.
Asked if he was comfortable with giving private security operatives the right to "shoot to kill" if necessary, Mr Cameron told BBC1's Andrew Marr Show: "We have to make choices.
"Frankly, the extent of the hijack and ransom of ships round the Horn of Africa is a complete stain on our world.
"The fact that a bunch of pirates in Somalia are managing to hold to ransom the rest of the world and our trading system is a complete insult and the rest of the world needs to come together with much more vigour."
France and Spain provide so-called military vessel protection detachments, while Italy is planning a similar measure.
However, in July, Foreign Office Minister Henry Bellingham said limited resources in the light of current military commitments could not allow Royal Marines to do the same.
Under the plans, the Home Secretary will be given the power to license vessels to carry armed security, including automatic weapons, currently prohibited under firearms laws.