Gambian President Yahya Jammeh has issued a harsh warning to criminals in the tiny African nation, telling security chiefs to "shoot first and ask questions later".

He told a meeting of the National Security Council on Tuesday night that he wanted all non-Gambian criminals out of the country, warning diplomats that "no form of diplomacy, aid or friendship will make me allow people to destroy this country.

"Anybody who thinks that your people are criminals, tell them to stay in your country because if they come to Gambia, they are asking for trouble," Jammeh said.

"Drug dealers, paedophiles, homosexuals, murderers, drug traffickers ... we are not going to tolerate that in this country whether black or white, I don't care," Jammeh told the meeting.

"For armed robbers, shoot first and ask questions later and if anybody has an objection on that, let him or her come and ask me."

The meeting, which was called to address what officials said were recent "heinous crimes committed in the country," lasted more than six hours.

The crimes referred to include the murder of a British national by three people suspected to be Nigerians and an attack on a Lebanese businessman who was seriously injured in an attempted murder two weeks ago.

They also refer to the arrest of 19 people, including Gambians, Senegalese and Nigerians "suspected of homosexuality" in April.

Jammeh's comment comes barely a month after he warned diplomats in an address to parliament that his country would not be "bribed" with aid to allow homosexuality.

"If you are to give us aid for men and men or for women and women to marry, leave it. We don't need your aid because as far as I am the president of Gambia, you will never see that happen in this country," Jammeh said then.

Gambia's treatment of gays has long drawn criticism from international observers, who accuse the small west African nation of egregious homophobia.

Jammeh, who has repeatedly denounced the practice, in 2008 even vowed to behead gays -- a threat he later retracted.