A Saudi businessman who has bought a 30% stake in the Independent appears to have links to the country’s government, raising questions about whether the deal could affect the news site’s editorial independence.

The Guardian understands that Sultan Muhammad Abuljadayel works for NCB Capital, the investment banking arm of the National Commercial Bank, which is controlled by the Saudi government and is one of the biggest banks in the Middle East.

In a move that highlights the concerns about the deal, Abuljadayel is understood to have had to sign a declaration that his investment is personal and that he is the ultimate beneficial owner of the Independent shares.

News of Abuljadayel’s stake emerged last week, sparking concerns that the website’s liberal political stance and hard-hitting coverage of Saudi Arabia’s human rights record and foreign policy could change.

Saudi Arabia’s suppression of freedom of speech has been heavily criticised. It is one of several Middle Eastern countries that has demanded the closure of the broadcaster al-Jazeera in return for lifting a blockade of Qatar.

Little was known about Abuljadayel when his investment in the Independent was revealed. Companies House filings say he is 42, based in Saudi Arabia, and appears to have no other UK business interests.

He bought his shares from multiple investors. The deal means the shareholding of Evgeny Lebedev, the owner of the Independent’s parent company, ESI Media, has fallen to 41%. Justin Byam Shaw, an entrepreneur and chairman of ESI, owns 26%, and the rest is held by smaller investors.

It has been reported that Abuljadayel inherited his wealth and is from a family with international property investments. The Guardian has seen information showing that Abuljadayel is a manager at NCB Capital.

ESI declined to comment on Abuljadayel’s role at NCB Capital and Lebedev said he was not concerned about the possibility of editorial interference.

While some journalists at the Independent have expressed unease about the Saudi’s investment, others say they are confident that editorial independence will not be compromised. “We want to compete by breaking good stories from anywhere in the world. I don’t see that changing,” one source told the Guardian.

Abuljadayel has not been given a seat on the board and a new agreement between the shareholders is designed to guarantee the editorial independence of the publication.

Lebedev said: “I am not remotely concerned about the prospect of editorial interference by a minority shareholder or anyone else.

“We have recently formalised the editorial independence of the Independent in our shareholders’ agreement and I think you will agree that our coverage of the Middle East continues to be as good and as independent as any UK news outlet and more robust than most.”

Lebedev announced in February 2016 that the Independent and Independent on Sunday would cease printing newspapers and continue online only. He told staff the move “preserves the Independent brand and allows us to continue to invest in the high quality editorial content that is attracting more and more readers to our online platforms”.

Since then, the Independent has reported a surge in online traffic in both the UK and US and it now has about 100 million unique users a month.

The latest financial results for Independent Digital News and Media show it recorded a £1.7m pre-tax profit in the year to 2 October 2016, up from £1.3m the previous year. Revenue almost doubled from £8.2m to £14.3m. The Independent’s digital operation employed an average of 49 people last year and ran up a wage bill of £5.5m, including directors.

Abuljadayel did not respond to requests for comment.