As many as 30 Trump administration appointees may be in violation of ethics guidelines intended to prevent officials from working in agencies they once lobbied, a government watchdog said Monday.

The appointees include a top federal health official who worked for medical supply interests, an Office of the U.S. Trade Representative official who previously lobbied for U.S. Steel Corp. and a Pentagon official who lobbied for a military software company seeking defense contracts.

Public Citizen, a non-profit consumer protection and government accountability advocacy group, filed 30 ethics complaints against the agencies and the White House after the group identified dozens of appointments in the Trump administration that it says appear to violate one of the president's ethics rules.

As a result of a report titled The Company We Keep, the group sent letters requesting that each of the respective designated agency ethics officers investigate and respond to the 30 identified appointments of individuals the group identified as lobbyists.

In letters sent to the agency and office heads on Monday, the organization argued that hiring people who lobbied for interests directly related their new government offices, absent a formal waiver, violates President Trump’s own ethics guidelines.

During his first week in office, Trump issued an executive order requiring all administration appointees to sign an ethics pledge that, in part, addressed previous work as lobbyists. Public Citizen said the ethics order surprised many and used some of the same key provisions from President Barack Obama’s earlier ethics executive order.

"I will not for a period of 2 years from the date of my appointment participate in any particular matter involving specific parties that is directly and substantially related to my former employer or former clients, including regulations and contracts," the agreement under Trump reads.

Officials in violation of Trump's ethics order can recuse themselves, or bypass the restriction by way of an ethics waiver.

ABC News has requested comment from the White House.

Public Citizen identified 133 executive branch appointees who had previously served as registered lobbyists during their professional careers, including 60 who worked actively as lobbyists during the two years prior to joining the federal government.

Of those, Public Citizen said 36 appointees had specifically lobbied the agencies where they now work, and only six had obtained the needed waiver.

“Violations of Trump’s ethics rules by the remaining 30 former lobbyists would occur if they are in any way involved in influencing official actions on the matters that they had recently lobbied in the private sector and have not received a waiver,” said Public Citizen in a statement.

The letters sent to 18 departments and agencies target high-ranking officials from the Department of Transportation, Homeland Security, Health and Human Services, Labor, Interior, Housing and Urban Development, Commerce, Justice, Energy, Education, Agriculture, Defense, Treasury, the EPA, the National Economic Council, the U.S. Trade and Development Agency, the Office of Management and Budget, and the Office of U.S. Trade Representative.

Among them was Keagan Lenihan, whom Trump appointed to a senior post at Health and Human Services. Lenihan had lobbied on behalf of drug giant McKesson Corporation and its affiliate, U.S. Oncology from 2011 to 2016. In his current post, he advises the secretary who oversees the agency in charge of creating national drug policies.

A representative for Lenihan at HHS was not immediately available for comment.

Pentagon appointee Justin Mikolay lobbied in 2015 and 2016 for Palantir Technology -- a silicon valley data firm. Palantir has previously lobbied for and received, government contracts for software used by defense and intelligence agencies.

Mikolay’s current post as special assistant and director of communications to the Secretary of Defense means that while he now works for the agency that oversees the government contracts for which he previously lobbied.

A representative for Mikolay in the Office of the Secretary of Defense was not immediately available for comment.

The complaints also cover Stephen Vaughn, the general counsel to U.S. Trade Representative. From 2014 to 2015, Vaughn lobbied for U.S. Steel on trade laws.

In his current role, Vaughn provides legal advice to the agency that makes international trade agreements, resolves trade disputes, and provides recommendations to the president on the country's trade policy.

A representative for Vaughn at the agency was not immediately available for comment.

“The bottom line is that neither Trump nor his administration take conflicts of interest and ethics seriously,” said Lisa Gilbert, vice president of legislative affairs for Public Citizen. “‘Drain the swamp’ was far more campaign rhetoric than a commitment to ethics, and the widespread lack of compliance and enforcement of Trump’s ethics executive order shows that ethics do not matter in the Trump administration.”

Public Citizen says there may be more administration officials in violation of the ethics pledge.

“These 30 apparent violations of Trump’s own ethics rules are only the tip of the iceberg,” co-author of the report and lobbyist for Public Citizen’s Congress Watch division Craig Holman said in a statement.

“We looked at only a quarter of all presidential appointees because records were not readily available at the time. I suspect the real number of potential violations is four-fold," Holman added.