Kurdish Peshmerga forces have requested UK help protect themselves from Isis chemical attacks as they ready themselves to help seize Iraqi city Mosul from the jihadist group.

Isis (Daesh) seized control of Mosul, Iraq's second biggest city, in 2014, and have established it as their base of operations in the country.

The final push to wrest control of the city back from Isis is expected to start within weeks, with Peshmerga forces to play a leading role.

In a letter to Defence Secretary Michael Fallon seen by the Guardian, the Kurdish high representative in the UK, Karwan Jamal Tahir, requested specialised equipment to help counteract the effects of chemical weapons, which he claimed had been used against Kurdish forces on 19 separate occasions by Isis.

Daesh has used chemical weapons including chlorine and mustard gas on several occasions in Iraq and Syria, CIA director John Brennan said in February.

In April, Foreign policy reported that Kurdish forces had urgently requested gas masks from Western allies following suspected mustard gas attacks on outposts in northern Iraq. According to the report, only 6,000 of the 65,000 Kurds fighting Isis had gas masks for protection against chemical attacks.

In September, The US has bombarded an Isis chemical weapons plant that was housed in a converted Iraqi pharmaceutical factory in the vicinity of Mosul, US Air Force commander Jeffrey Harrigian said.

Hayas Surji, a member of the Patriotic Union of Kurdistan, said on Monday that Isis was transferring chemical weapons from Syria into Mosul in anticipation of an assault on the city, Turkey's Anodolu news agency reported.