A “small, specialist team” is operating in Arbil, the capital of Iraq’s autonomous Kurdistan region, training peshmerga how to use the heavy machine guns Britain supplied in September.
The deployment was approved by Defence Secretary Michael Fallon, a ministry spokeswoman said.
“The government has previously made clear its intention to provide training to the peshmerga as part of the continued effort to assist in the fight against ISIL (Islamic State),” the spokeswoman said.
“The defence secretary has approved the deployment of a small, specialist team of non-combat army trainers which is now in the Arbil area providing instruction on operating, employing and maintaining the heavy machine guns that were gifted by the UK last month.”
The Sunday Times newspaper reported that the soldiers were from 2nd Battalion the Yorkshire Regiment, light role infantry whose headquarters are at the British sovereign base on Cyprus.
Royal Air Force Tornado jets have been taking part in bombing raids on Islamic State targets in Iraq.
British Prime Minister David Cameron has ruled out putting “combat boots on the ground” in the campaign to defeat the extremist group.
British forces were part of the US-led invasion of Iraq in 2003 that overthrew dictator Saddam Hussein. The last British combat troops left in 2009, with a small number staying on until 2011 to train Iraqi forces.
The UK is among more than 40 nations that have joined forces to challenge the militant group.
Countries including the US have also taken part in air strikes against militant positions in Syria, but the UK military effort has so far been confined to Iraq.
In Syria, an intense battle is taking place for Kobane, a strategic town on the country’s border with Turkey.
At least 553 people are reported to have died in a month of fighting, the Syrian Observatory for Human Rights said. The UK-based Syrian opposition body counted 298 IS fighters among the dead.
US aircraft have bombed IS positions but Kurdish leaders said they remain outgunned on the ground.
Kobane official Idris Nassan said that “the supply of fighters is very good”.
“But fighters coming without arms, without weaponry, is not going to make a critical difference,” he added.
Germany has given assault rifles and portable anti-tank rocket launchers to Kurdish forces and German troops have also been in the Arbil area training them to use that new weaponry.