A group of MPs including the former Conservative party leader Iain Duncan Smith have asked ministers to use national security law to investigate the Barclay family’s proposed deal to give control of the Telegraph to a consortium backed by the United Arab Emirates.

The group of 18 MPs, which also includes Alicia Kearns, the chair of the foreign affairs committee, have written to the deputy prime minister, Oliver Dowden, arguing that the proposed deal poses a “very real potential national security threat”.

Under the planned deal, RedBird IMI – a joint-venture between the US company RedBird Capital and International Media Investments (IMI) of Abu Dhabi – has agreed to repay the Barclay family’s debts to Lloyds, which seized control of the titles in June.

IMI is the investment vehicle for Sheikh Mansour bin Zayed al-Nahyan, the vice-president of the UAE, which also provides most of the funding for Redbird IMI.

The MPs’ call comes as Lloyds, the Barclay family and RedBird IMI, the Abu Dhabi-backed vehicle, are set to deliver a letter to Lucy Frazer, the culture secretary, giving her 48 hours’ notice that the £1.16bn loan is ready to be repaid.

Frazer is due to make a decision by Friday on whether to launch a formal investigation involving Ofcom and the competition regulator into the proposed deal on public interest grounds.

However, the group of Tory MPs argue that the government should also invoke the National Security and Investment Act to fully investigate the deal, which they said would result in the Telegraph and the Spectator passing “into majority ownership by the UAE government”.

The letter said: “During a time of increased geopolitical tensions, information warfare is more relevant than ever. And with the UAE’s increasingly influential position as a mediator and power broker, the risk for interference in Britain’s national conversation seems self-evident if the acquisition goes ahead.

“The influence it would give to a foreign government that is strengthening its relationship with Beijing at a time of growing tensions is even more troubling.”

The signatories note that, in the US, the committee on foreign investment is examining a number of deals involving UAE investment funds on security grounds.

“Taking action under the NSI Act would not prejudice the bid and those involved in it,” the letter stated. “It would enable the government to gather the necessary information and examine the proposed transactions in detail.”

However, it is unclear what grounds there are to launch an investigation using the NSI Act, which came into force at the beginning of last year and was designed to give the government more power to protect critical infrastructure assets.

The Act covers 17 sectors including communications, however newspapers are not listed as a media type covered.

In a 111-page government response to a consultation on the NSI bill, before it became an Act, it said: “Other news media (eg: newspapers) are not electronic communication networks or services and also do not fall within this sector definition.”

The letter, sent on Wednesday, follows a similar letter by a group of MPs who wrote to Dowden earlier this month.

Last week, it emerged that senior figures at the Foreign Office sought to “take the edge off” the public interest intervention letter Frazer is “minded” to enact by Friday, because it is eager to bolster Britain’s relations with the UAE.

RedBird IMI is led by Jeff Zucker, a former chief executive of CNN, who has repeatedly given assurances that if the fund took control of the Telegraph it would not seek to exert influence or control over editorial content or operations.

Zucker has said that IMI, which the sheikh controls, would remain a “passive” investor and is only involved “at the entrance of making the investment and at the exit”.

The former foreign secretary Lord Hague and Lord Moore, the former editor of the Telegraph, have also said the deal should not be allowed to proceed as the UAE’s free speech laws and controversial diplomatic positions on Russia and China mean it should not be able to influence a major British media company.