The United Kingdominfo-icon exported 500 cluster bombs to Saudi Arabiainfo-icon in the 1980s which the country used in its warinfo-icon on Yemeninfo-icon, an official report shows.

"The UKinfo-icon delivered 500 BL755 cluster munitions under a government-to-government agreement signed in 1986. The final delivery was made in 1989," reads a letter by Defense Secretary Michael Fallon to Conservative MP Philip Hollobone.

In December, Fallon said that a "limited number" of British cluster munitions were being used by Saudi-led forces in Yemen. In the same month, Saudi Arabia itself admitted to using the British weaponsinfo-icon against its southern neighbor.

Even though Riyadh has told the British government that it would no longer use the weapons, it has not yet confirmed that they were destroyed, Foreign Office Minister Tobias Ellwood told the House of Commons on Tuesday.

"The fact so many British-made cluster bombs were sold and are now being used in Yemen is a stain on the UK's reputation worldwide," said Liberal Democrat shadow Foreign Secretary Tom Brake.

"Michael Fallon has an urgent responsibility to address this shameful legacy, by suspending arms sales to the Saudi regime and putting pressure on it to stop using these horrific weapons."

"Most people are rightly sickened by the bombing of innocent civilians in Yemen. Our Government must end its complicity in this brutal conflictinfo-icon immediately," he added.Massive British arms sales to Saudi Arabia have come under scrutiny for months due to the kingdom's role in inflicting heavy civilian casualties through the kingdom's bombing campaign across Yemen.

Saudi Arabia's aggression against Yemen, which began in March 2015, has so far killed at least 11,400 Yemenis.

In November, the UK rejected calls by two parliamentary committees and human rightsinfo-icon groups to stop selling arms to Saudi Arabia.

Amnesty Internationalinfo-icon on Monday called for "an immediate suspension of all further weapons sales to Saudi Arabia."

Amnesty has previously accused British Prime Minister Theresa May of being blase about the issue, given the "clear risk that UK weapons could be used to commit breaches of international humanitarian law in Yemen."

The UK is a signatory to the 2010 Oslo treaty banning cluster munitions, which are designed to release dozens of smaller bombs over a wide area. The smaller munitions do not always explode, posing a future risk to civilians.The UK has also been involved in training Saudi forces in air warfare skills and artillery.

The prime minister of Yemen's rebel Houthi government has accused the UK of war crimes for supplying arms to the coalition, which is conducting military operations to restore the regime overthrown last year.

Saudi Arabia intervened in Yemen in March 2015, launching airstrikes in order to stop Houthi advances and reinstate ousted Sunni President Abd-Rabbu Mansour Hadi to power.

Riyadh is backed by a coalition of nine Arab countries, which has been armed by the UK and USinfo-icon, while the Houthis are aided by Iraninfo-icon.

Up to 10,000 people have been killed so far since fighting began in Yemen, including 4,000 civilians, according to UN estimates.

The UN stated in August that the Saudi-led coalition is responsible for a majority of the civilian deaths, while calling for an international investigation into the coalition's violations in Yemen.