Nick Seddon, former special advisor for health to David Cameron, has joined US-based firm Optum.

Seddon, who served in the role until July 2016, became executive vice-president at the company in November, it has emerged.

The move was reported by Vice News on Thursday and is covered in Downing Street 'transparency information' documents published just before Christmas.

Part of the UnitedHealth Group, Optum currently provides services to 156 NHS organisations.

Opponents of NHS privatisation have criticised Seddon’s appointment, which adds fuel to the flames for campaigners who fear healthcare provision could be part of a UK-US trade deal post-Brexit.

On Wednesday, Theresa May emphasised that “the NHS is not for sale and it never will be”.

UnitedHealth Group provides medical and insurance services in 50 US states and 125 other countries. Its operating earnings for 2016 exceeded $13 billion (£10 billion).

Seddon was formerly head of communication at Circle Health from 2008 to 2010, and then director at think-tank Reform until 2013.