The EU said Friday it has tightened rules to prevent horsemeat inadvertantly or fraudulently ending up in food across the bloc and avoid a repeat of last year's scandal.

The European Commission said revised rules will require all horses before their first birthdays to be implanted with microchips, a kind of passport that must now be entered into centralised databases in all 28 member states.

"The introduction of a compulsory centralised database in all member states will assist the competent authorities to better control the issuance of the passports by different passport issuing bodies," the Commission, the European Union's executive arm, said in a statement.

Not all countries, particularly Britain and Sweden, had such databases, EU sources said.

Under the new rules, all horses born after July 1, 2009 will also have to have microchips implanted in them.

The new regulations will take effect in January 2016, while countries that do not have centralised databases will have until July 2016 to set one up, the Commission said.

The chips will serve as a medical record that would reveal whether a horse has been treated with bute or other medicines that disqualify the animal to be used for food consumption.

"As promised, this is another lesson drawn from last year's horse meat fraud: the rules endorsed by the member states will strengthen the horse passport system in place," EU Health Commissioner Tonio Borg said.

"I believe that closer cooperation will enhance the safeguards which prevent non-food quality horse meat from ending up on our plates," he said.

The scandal started in January last year, when beefburgers sold in several British and Irish supermarket chains were found to contain horsemeat, before spreading to more than a dozen other countries.

Thousands of DNA tests on European beef products showed more than 4.5 percent were tainted with horsemeat after cases across Europe sparked consumer outrage and forced companies into costly product recalls.

A separate test of horse carcasses showed just over 0.5 percent were positive for phenylbutazone, a painkiller for horses potentially harmful to humans.

Borg and other officials insisted last year the core problem was one of fraud -- horsemeat being passed off as beef -- and not food safety.