The announcement by George Robertson, Secretary of State for Defence, anticipates an international law on the issue. He is trying to put pressure on countries, including the US, Russia, China, India, Turkey and Pakistan, that have failed to sign the Ottawa Convention banning the weapons.
Mr Robertson declared the prohibition on mines ahead of the anniversary of the death of Diana, Princess of Wales, a leading figure in the campaign to ban them.
British forces introduced a moratorium on mines in May last year, but they could have been used in "exceptional circumstances". From yesterday there will be no exemptions.
In answer to Chris Mullin, Labour MP for Sunderland South, Mr Robertson said that orders had been issued to all Command Headquarters and training establishments banning mines.
"We intend this to be an international example to others," Mr Robertson said.
Britain is already destroying stockpiles and helping in "de-mining" projects throughout the world.
Earlier Mr Robertson said the Government was making a concerted effort to persuade other countries to sign the treaty, expected to come into force later this year.
He told BBC Radio 4's Today programme: "The most professional army in the world now has said that this is not a system that is morally correct or militarily useful.
"There is a huge problem out there of countries who have still not signed. We must use Britain's moral authority to make sure our position becomes the international standard."
Ian Bray, of Oxfam, welcomed the Government's decision and said that the previous policy of allowing the use of the weapons in exceptional circumstances constituted a "huge anomaly".
Forty countries would need to sign the convention before it passed into international law. By yesterday 37 nations had signed. Mr Bray pointed out that the US was refusing to adopt the policy because it contends that it needs to use anti-personnel landmines in Korea. But America has indicated it was seeking alternatives to the weapons and aimed to ratify the treaty by the year 2002.
Lou McGrath of the Mines Advisory Group, a charitable organisation involved in clearing operations in Angola, Northern Iraq, Cambodia, Laos and Vietnam, believes the British Army could still encounter problems. He pointed out that the UK was often involved in Nato operations with the USA and Turkey both of which would still deploy the weapons.
Mines were last used by the United Kingdom in the Gulf War when they were dropped by Tornado jets on Iraqi airfields.Reuse content