Acting defense secretary Patrick Shanahan at the Pentagon on March 12. (Carolyn Kaster/AP)

A government watchdog group has asked the Pentagon’s inspector general to open an investigation into whether acting defense secretary Patrick Shanahan, a former Boeing executive, violated ethics rules in his handling of matters related to his former employer.

Shanahan became the Pentagon’s No. 2 official in 2017 after a long career at Boeing, the aviation company that is a major supplier for the U.S. military. President Trump is considering nominating him to be confirmed in the top Pentagon job, which he has held in an acting capacity since predecessor Jim Mattis resigned abruptly late last year.

In its letter to the Pentagon’s inspector general, Citizens for Responsibility and Ethics in Washington (CREW) said that Shanahan had, according to news reports, appeared to have “made numerous statements promoting his former employer Boeing and has disparaged the company’s competitors before subordinates at the agency.”

The group cited news stories reporting that Shanahan had criticized Lockheed Martin, a chief rival to Boeing, and had urged the Pentagon to buy more Boeing-manufactured F-15X fighter jets in defiance of Air Force acquisition preferences. The Washington Post has not independently confirmed those reports.

“If the statements attributed to Acting Secretary Shanahan are accurate, he appears to have violated the prohibition on using public office for private gain by using his position or official authority to explicitly endorse Boeing,” CREW said.

CREW also raised questions about lucrative aviation contracts awarded to Boeing during Shanahan’s tenure.

Lt. Col. Joe Buccino, a spokesman for Shanahan, said the acting secretary had “at all times remained committed to complying [with] his ethics agreement, which screens Boeing matters to another [Pentagon] official and ensures no potential for a conflict of interest with Boeing on any matter.”

The request comes as Boeing faces global scrutiny for its 737 Max 8 aircraft, which has suffered two deadly crashes in recent months. Trump grounded the aircraft on Wednesday, after several countries issued similar bans this week.

Speaking briefly to reporters on Tuesday, Shanahan urged trust in the Federal Aviation Administration.

The CREW request was first reported by the Military Times.