Rinat Akhmetshin was not one to hide his connections to Russian intelligence.

During his years working in the shadowy Washington DC world of corporate intelligence, his connections to former Russian agents were pitched as a valuable asset to private clients. Akhmetshin – who courted journalists and politicians alike – was known for speaking as candidly about his years of military service in Afghanistan as his objectives on Capitol Hill.

Ex-Soviet counter-intelligence officer says he attended Trump Jr meeting Read more

On Friday, Akhmetshin, who is an American citizen, said that he also attended the 2016 meeting with Donald Trump Jr described as part of a Russian government attempt to undermine Hillary Clinton’s election campaign. The revelation raises new questions about the purpose of the encounter, and why the president’s son – who promised to be transparent about the meeting in Trump Tower – did not admit that Akhmetshin was also in the room.

Akhmetshin began his career working for central Asian oligarchs who needed a helping hand in Washington for one problem or another. But in recent years, his lobbying work seemed to take on a singular focus: reversing the 2012 Magnitsky Act, a law passed by Barack Obama that infuriated Russia’s president, Vladimir Putin, and was designed to punish Russia for the 2009 prison death of the Russian lawyer Sergei Magnitsky.

One attorney who knows Akhmetshin and has hired him in the past said that far from being seen as pro-Putin, the Russian American lobbyist assiduously avoided politics. In his business dealings with prospective clients, however, he used his connections to Russian intelligence as a selling point.

“His background and history was an asset he sold to clients, whoever came into the door. He has quite a diverse group of clients,” the person said, adding: “I know he was engaged by people who wanted to get rid of Magnitsky [Act].”

“He is a former GRU person for sure, but he once said there is no such thing as former,” the person added with a laugh.

That fact that Akhmetshin, who told Politico last year that he once served as a Soviet counter-intelligence officer, is an American citizen also suggests that he would have at least been known to US officials.

Akhmetshin did not respond to calls or emails from the Guardian. But in an exchange in May, the lobbyist downplayed the Russia-Trump scandal, telling a reporter he did not believe that the Kremlin was involved in colluding with the Trump campaign and that allegations of frequent contacts between Russian agents and Trump campaign officials had probably been fabricated.

At the same time, he acknowledged that he was facing scrutiny on Capitol Hill for his efforts to reverse the Magnitsky Act, which has made him a target of the Iowa Republican Chuck Grassley.

It isn’t the first time he has been in hot water. Akhmetshin is not registered as representing foreign agents or governments, but his client list is long. Over the years it has included members of Kazakhstan’s political opposition. He was also accused in a US lawsuit of engaging in a campaign to encourage US officials to reverse the asylum status of Ashot Egiazaryan, a former deputy of the Russian Duma.

Last year, Akhmetshin was seen walking around Congress by a congressional staffer, Kyle Parker, who was described by Politico as the driving force behind the original Magnitsky Act. Parker reportedly warned colleagues that he was alarmed because Akhmetshin was known for specialising in “active measures campaigns”.

Confronted with the allegation, Akhmetshin seemed to shrug it off, telling Politico: “Just because I was born in Russia doesn’t mean I am an agent of the Kremlin.”