The State Department spent more than $15,000 to book 19 rooms at the new Trump hotel in Vancouver when members of President Donald Trump's family headlined the grand opening of the tower in late February.

The hotel bookings - which were released to The Washington Post under a Freedom of Information Act request - reflect the first evidence of State Department expenditures at a Trump-branded property since Trump took office in January.

The department redacted many of the details on the invoice from the US Consulate General in Vancouver and declined to provide additional information about the nature of the State Department's presence at the hotel. Although the Secret Service is responsible for protecting the president's family, the State Department provides assistance with security and logistics for international trips.

The President's sons, Donald Jr and Eric, their spouses, and the president's daughter, Tiffany, were flanked by a heavy security presence on 28 February during a ribbon-cutting ceremony and a VIP party hosted by developer Joo Kim Tiah, the son of one of Malaysia's wealthiest businessmen.

Since his inauguration, Trump has spent much of his free time at his private business properties, ranging from his Mar-a-Lago club in Florida to his golf courses in Virginia and New Jersey. Meanwhile, Trump's sons - Donald Jr and Eric - have travelled to Dubai, Vancouver, Uruguay and Ireland to promote the family's real estate empire.

Such business trips by Trump's children have put US government agencies in a necessary - albeit potentially awkward - arrangement of engaging in taxpayer-funded transactions with the president's private company while at the same time protecting the president's immediate family. The president has refused critics' demands to divest his assets and has instead placed his business empire into a trust controlled by sons Don Jr and Eric.

Last week, the outgoing head of the Office of Government Ethics, Walter Shaub Jr, told CBS News that he believes there is “an appearance that the businesses are profiting from his occupying the presidency.”

The Trump Organization does not own the Trump International Hotel and Tower in Vancouver but instead has a management and licensing deal. Trump's most recent financial disclosure reflects that he earned more than $5 million in royalties from the Vancouver project during the last reporting period, which covers the year 2016 through April 2017.

A State Department official did not answer questions about who stayed at the Trump hotel and the reasons for their stay.

“Embassy and consulate personnel work with the Secret Service to provide assistance on security matters as necessary for conditions in the particular host country,” the official told The Washington Post. “Our policy is not to discuss the details of security matters.”

A spokeswoman from the Trump Organization declined to answer questions about how the Trump family paid for their rooms and what type of assistance the State Department provided the family on their business trip.

Secret Service spokesman Joseph Casey told the Post it is common to “utilise our partners at the State Department to assist us in facilitating our security plan” for international trips.

In March, The Post filed a separate Freedom of Information Act request with the Secret Service seeking similar records of expenses from the Vancouver trip. The agency has not yet released the records, which would likely reflect a bill for additional rooms separate from those reserved by State Department staff.

The Post previously reported that the Secret Service spent $88,320 for lodging on Eric Trump's business trip to Uruguay in early January to promote a Trump hotel and condominium tower under construction in the resort town of Punta del Este.

The State Department - through the US Embassy in Montevideo - paid an additional $9,510 for hotel rooms to assist the Secret Service for the visit, according to purchasing orders.

The 28 February grand opening of the Vancouver hotel drew crowds of protesters who chanted and held signs outside of the hotel. Guests and the media were ushered inside through a back entrance of the “twisting tower,” which is known for its striking shape among the Vancouver skyline.

Once inside, members of the press were offered a tour of the luxury property, including lavender-scented hand towels at the Ivanka Trump-branded spa and handcrafted cocktails at the lobby bar.

The Post requested any records related to the use of State Department funds to provide security or other services for the Trump family's trip to the Vancouver hotel.

The department's expenditures reflect a total of 56 nights booked at the Trump hotel in Vancouver. Four rooms were booked for seven nights, while the remaining rooms were booked for either one or two nights.

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The records released to The Post were heavily redacted because of security and privacy exemptions. The names of the staffers and their assignments were not disclosed, nor were the specific rates of the rooms.

The State Department also spent $5,000 for rooms at a nearby Hyatt Regency, which is about a five-minute walk from the Trump hotel.