The Government has been asked to reveal what steps it has taken to investigate whether Manchester City owner Sheikh Mansour assisted wealthy Russians it has sanctioned in moving their assets to the United Arab Emirates.

Lawyers acting on behalf of a Ukrainian activist – who wishes to remain anonymous for fear of reprisals from Russia – have written to Foreign Secretary James Cleverly to ask whether investigations have been carried out to determine whether Mansour, the UAE’s Deputy Prime Minister, should be identified as a ‘designated person’ subject to financial sanctions under the Russia (Sanctions) (EU Exit) Regulations 2019.

As of last week, the UK Government said more than 1,800 individuals had been sanctioned under the regulations, with more than 1,600 of those sanctioned since Russia launched its invasion of Ukraine in February 2022.

That number includes former Chelsea owner Roman Abramovich. His assets, including Chelsea, were frozen, with a consortium led by American businessman Todd Boehly taking over the Premier League club last summer.

The request for an update on Sheikh Mansour follows an initial letter from the lawyers, Rhys Davies of Temple Garden Chambers and Ben Keith from 5, St Andrew’s Hill Chambers, on behalf of their client which was sent to Cleverly in September last year.

The Foreign Secretary can only designate a person if he has reasonable grounds to suspect that the individual is “an involved person” in the destabilisation of Ukraine.

Involvement is defined as someone who is responsible for, engages in, provides support for, or promotes any policy or action which destabilises Ukraine or undermines or threatens its territorial integrity.

If Sheikh Mansour was designated as an individual subject to Government sanctions, it would disqualify him as an owner under the Premier League’s updated rules on its owners’ and directors’ test which were published in March.

The new letter, sent to Cleverly on Thursday and seen by the PA news agency, states: “Sheikh Mansour is a particularly high-profile individual and as the owner of one of the United Kingdom’s most celebrated football clubs, is a person who ought to be subject to reasonable scrutiny by the UK Government.

“For the avoidance of doubt, we make no allegations as to any particular conduct of Sheikh Mansour. Nevertheless, in light of the wealth of evidence in the public domain tending to link Sheikh Mansour with the accommodation of wealthy Russians in the UAE, we respectfully suggest that there is a prima facie basis for the UK government to conduct an investigation.”

The new letter has been sent as the UAE prepares to host the COP28 climate change conference between November 30 and December 12 and notes that Sheikh Mansour is likely to play a “visible role” in the event.

“The bloodshed caused by the Russian invasion of Ukraine continues,” the letter stated.

“You are asked to note that, as set out in our earlier correspondence, notwithstanding the robust nature of the British response to the Russian invasion of Ukraine, many Russian oligarchs appear to have found a home for their wealth in the United Arab Emirates, with Dubai and Abu Dhabi apparently being particularly attractive to those individuals.

“In light of the global attention which will be focused on both the UAE and Sheikh Mansour at the forthcoming COP28 event, we write to you to enquire what steps you have taken further to our request of September 30, 2022 to open an investigation into the conduct of Sheikh Mansour.

“You may recollect that we invited the UK government to consider whether or not the conduct of Sheikh Mansour is such that he is a suitable person to be designated, pursuant to the Russia (Sanctions) (EU Exit) Regulations 2019.

“In the circumstances, it is critical that the UK Government takes all necessary steps consistent with its statutory and international obligations.”

A spokesperson for the Foreign, Commonwealth and Development Office said: “The UK has stepped up diplomatic engagement with the UAE to address Russian attempts to evade sanctions, and we’ve since seen positive progress such as their recent delicensing of Russia’s MTS Bank.

“We will not tolerate attempts to help Russian oligarchs hide their assets in complex financial networks and in April introduced a sanctions package to crack down on their enablers.”

The FCDO does not comment on future designations.

The department is aware of Russian efforts to circumvent sanctions. It has stepped up engagement with third countries to raise concerns – including the UAE, Turkey, Kazakhstan, Uzbekistan, Kyrgyzstan, Georgia, Armenia and Serbia.

The key focus of that engagement to date has been on disrupting Russian efforts to secure critical sanctioned goods needed in weapons manufacture.

The UAE’s Ministry of Foreign Affairs and Manchester City have also been contacted for comment.