The Government has broken a court ruling banning it from granting licences to export weapons and equipment to Saudi Arabia.
More than 180 items worth £261,450 have been shipped in the "inadvertent" breaches of an assurance it would not licence any more arms sales to Saudi Arabia.
Yemen is in the grip of a civil war which sees the Saudi-backed Government battling Houthi rebels.
The UN says the conflict has claimed the lives of at least 7,290 civilians and left 80% of the population - 24 million people - in need of humanitarian assistance or protection, including 10 million who rely on food aid to survive.
The pause came while the Government considered the Court of Appeal's ruling that it had failed to assess whether the the Saudi-led coalition had violated international humanitarian law in the course of the Yemen conflict.
International Trade Secretary Liz Truss said routine analysis of licensing statistics found a licence for a £200 air cooler for a Renault Sherpa Light Scout vehicle had been issued to the RSLF just days after the ruling.
A subsequent review identified another licence for the export of 260 items of radio spares for the RSLF Signals Corps valued at £435,450 had been issued in July.
To date, 180 items worth £261,450 have been shipped.
In a letter to the Commons Committees on Arms Export Controls, Ms Truss said the Department for International Trade (DIT) was in the process of revoking the licence as “a matter of urgency”.
“I have apologised to the court unreservedly for the error in granting these two licences,” she said.
She said an internal investigation had been launched to establish whether any other licences had been issued in breach of assurances to the court or to Parliament, and to ensure there could be no further breaches.
Andrew Smith, of Campaign Against Arms Trade, which brought the original court case, said: “We are always being told how rigorous and robust UK arms export controls supposedly are but this shows that nothing could be further from the truth.
“The reality is that, no matter how appalling the crisis in Yemen has become, the Government has always been far more concerned with arms company profits than it has with the rights and lives of Yemeni people.”
This comes as US President Donald Trump has thrown his weight behind the Saudis, after a drone attack on the Middle Eastern country's - and the world's - biggest oil processing plant on Saturday
A Department for International Trade spokesperson said:“We very much regret that the licences were issued in error. The International Trade Secretary commissioned a full and urgent investigation as soon as the breach was discovered.
“Throughout the investigation, all decisions made on export licences to Saudi Arabia and its Coalition partners will be subject to additional compliance checks, including closer collaboration between departments, so that no further licences are issued in error.
“We take our arms export control responsibilities very seriously and remain fully committed to complying with the Court Order.”