A Democratic senator warned 2 July that the United States could cut off arms sales to the UAE if proven that it shipped US missiles to Libyan rebels, as the US ally denied it was involved.

In a letter to Secretary of State Mike Pompeo, Robert Menendez, the top Democrat on the Senate Foreign Relations Committee, demanded an investigation and asked for explanations by 15 July on arms agreements with the UAE.

‘You are surely aware that if these allegations prove true you may be obligated by law to terminate all arms sales to the UAE,’ Menendez said.

He warned that the transfer would be a ‘serious violation’ of US law and ‘almost certainly’ break the UN arms embargo on Libya.

The New York Times reported on 28 June that forces loyal to Libya's unity government had discovered four Javelin missiles at a base used by men under the command of Khalifa Haftar, who has waged a months-long offensive to take Tripoli.

The newspaper said that markings on the US-made missiles indicated they had been sold to the UAE in 2008.

The UAE foreign ministry on 1 July said it was committed to the UN resolutions on the arms embargo and said it was ‘denying the ownership of weapons found in Libya.’

‘The UAE also urges all parties to de-escalate tensions and to re-engage in the UN's political process,’ it said in a statement.

The US State Department earlier said that it took allegations of misuse of US weapons seriously and was seeking answers.

Menendez told Pompeo that the alleged arms transfer to Libya was ‘particularly alarming’ as it came shortly after President Donald Trump's administration bypassed Congress to approve $8.1 billion in arms sales to Saudi Arabia and the UAE.

Lawmakers fear that the weapons will be used to kill civilians in Yemen, where millions are on the brink of starvation and schools and hospitals have been hit in a Saudi and Emirati offensive.

Pompeo said that the sale was an emergency because of tensions with Iran, which backs Yemen's Houthi rebels.

Democratic senators and a handful of Republicans last month voted to block the sale but they did not have enough votes to override a veto by Trump.