China's highest court has issued new guidelines on the death penalty that instruct lower courts to limit its use to a small number of "extremely serious" cases.

The Supreme People's Court told courts to use a policy of "justice tempered with mercy" that takes into consideration the severity of the crime, the state-run Xinhua News Agency quoted court spokesman Sun Jungong as saying in a report late Tuesday.

The guidelines reflect the court's call last July for the death penalty to be used less often and for only the most serious criminal cases. China executes more people than any other country, but the high court has been more outspoken recently about the need to tone it down.

The court reviews all death sentences from lower courts before they are carried out, and its comments have indicated more of those death sentences could be overturned.

Still, China faced strong international criticism at the end of December when it executed a British man accused of drug smuggling, despite a plea for mercy from the British prime minister and concerns that the man had mental problems.

Rights group Amnesty International has said China put at least 1,718 people to death in 2008. China does not release an official count.