Apple CEO Tim Cook says he will investigate the Saudi government app branded "abhorrent" by a US senator following an investigation by Business Insider's sister site INSIDER.

INSIDER reported extensively how the online app Absher helps men control where women travel, pushing alerts when they use their passports to leave the country.

On Monday, Sen. Ron Wyden of Oregon wrote to Cook and Google CEO Sundar Pichai demanding that the app be "immediately removed" from the App Store and the Google Play Store.

Cook was asked about the app on Tuesday by National Public Radio. It was the first time Apple had addressed the app after it declined to respond to INSIDER's repeated requests for comment.

Read INSIDER's full reports on Absher and on the criticism aimed at Google and Apple from human-rights groups.

Apple CEO Tim Cook has pledged to get to the bottom of a Saudi government app hosted on the App Store that was labeled "abhorrent" by a US senator for helping men control where women travel.

While speaking with National Public Radio on Tuesday, Cook was asked about Absher, a benign-seeming government app that has been criticized for features meant to let Saudi men control where women travel.

"I haven't heard about it," Cook told NPR. "But obviously we'll take a look at it if that's the case."

Business Insider's sister site INSIDER has reported extensively on Absher, which pushes alerts to men when women use their passports.

It prompted Sen. Ron Wyden of Oregon into writing to Cook and Google's CEO, Sundar Pichai, on Monday. He said the app "flies in the face of the type of society you both claim to support and defend."

"American companies should not enable or facilitate the Saudi government's patriarchy," Wyden wrote, describing the Saudi system of control over women as "abhorrent."

Cook's comments to NPR are the first time Apple has addressed the app after it declined to respond to INSIDER's repeated requests for comment. Google has not acknowledged repeated requests for comment.

An Apple laptop on a lectern branded with the Google logo. REUTERS/Robert Galbraith

Under Saudi Arabia's guardianship laws, women must have a male representative to decide whether they can travel abroad. Absher is the digital manifestation of the system, and it is where men manage much of women's lives.

Wyden wrote his letter in response to two reports by INSIDER on Absher.

The first explained how the app works and how some women in Saudi Arabia were managing to get around it to claim asylum in other countries. The second highlighted criticism of Apple and Google by human-rights campaigners for hosting the app.

Read more: Q&A: The hurdles and obstacles Saudi female runaways face

On this Absher form guardians can say where women can go, how long for, and which airports they can go to. Absher

"Apple and Google have rules against apps that facilitate threats and harassment," Human Rights Watch's Rothna Begum told INSIDER. "Apps like this one can facilitate human-rights abuses, including discrimination against women."

Yasmine Mohammed, an activist who is an outspoken critic of Saudi Arabia, said the companies were "facilitating the most archaic misogyny" and helped the Saudi government enforce "gender apartheid."

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The app has been downloaded 4.2 million times on the App Store and 5 million times on Google Play since launching in mid-2015, according to Apptopia.

92% of installs happened in Saudi Arabia but nearly 430,000 (5.5% ) have come from within the US, app researchers Sensor Tower told INSIDER.

A 2017 estimate from the US Census Bureau lists 82,201 Saudi nationals as living in the US.

The Saudi Interior Ministry, who made the app, responded to the wave of negative media coverage on January 17, criticizing attempts to "politicize" the issue. Here's the full statement:

"An official source at Interior Ministry said, in a repose of what is being circulated about the application of services (Absher), that these allegations aim to disable the benefits of more than 160 different procedural services to all members of the society provided by the Government of the Kingdom of Saudi Arabian to the citizens and residents, including women, the elderly, and people with special needs." "The Ministry strongly condemns the systematic campaign aimed at questioning the purpose of (Abshar) services, which is provided on smart phones to facilitate the services to its beneficiaries." "The Ministry of Interior at the same time confirms its rejection of the attempts to politicize the systematic use of technical instruments which represent legitimate rights to the users, and its keenness to protect the interests of the beneficiaries of its services."

Apple and Google hosted the Saudi crown prince last year

The app raises awkward questions for Apple and Google, two of the biggest players in Silicon Valley, where tech firms have well-established links to Saudi Arabia.

Both firms hosted Saudi Crown Prince Mohammed bin Salman last year. The crown prince got a rare tour inside the $5 billion Apple Park campus, in California, which included face time with Cook and other top executives.

Google CEO Sundar Pichai. Google has not yet responded to requests for comment from INSIDER. AP Photo/Eric Risberg

Read more: A look inside the daily routine of Apple CEO Tim Cook, who wakes up before dawn and gets up to 800 emails a day

During the visit, Crown Prince Mohammed was on a charm offensive, according to The New York Times.

The aim of the visit was to change Western perspectives on Saudi Arabia as a backward and conservative country dependent on oil money where women are treated as second-class people.

Instead, the crown prince, who is the kingdom's de facto ruler, wants Americans to see Saudi Arabia as a modern country with extensive investments in growth markets like technology.