Tiffany Trump went to Serbia during her spring break from Georgetown Law School during the second week of March.

It is believed she went to the country with her boyfriend, Michael Boulos, a London-based finance student she met in Greece last summer.

According to a purchase order from the State Department, $23,000 was requested for lodging in Belgrade, Serbia, between March 7 and March 16.

The order said the money was for hotel rooms at the Square Nine hotel in Belgrade, where rooms cost between $300 and $16,000.

President Donald Trump's youngest daughter Tiffany Trump took a trip to Serbia over her spring break from Georgetown Law School, and it cost US taxpayers at least $23,000.

According to a purchase order from the State Department first reported by Quartz, $23,000 was requested for lodging in Belgrade, Serbia, between March 7 and March 16.

The purchase order, titled "Acquisition of hotel accommodations in support of Tiffany Trump travel," was for rooms at the Square Nine hotel, which offers 30 rooms that range in price from $300 a night to $1,600.

Members of Trump's immediate family, including all of his children, are eligible for Secret Service protection when traveling.

In the purchase order for Tiffany Trump, the first daughter is called a "VIP" and a Senior High Level US Government Principal.

Read more: The glamorous life of Tiffany Trump, the president's lesser-known youngest daughter

The order said money would be used on security, communications, logistics, and operations during the trip to Belgrade. While the order said the funds would be used for 120 hotel rooms, that was over the course of 10 nights between March 7 and March 16, or 12 rooms per night.

It is believed she traveled to the country with her boyfriend, Michael Boulos, a London-based finance student who was raised in Nigeria. It is unknown if they stayed together at the Square Nine hotel.

Tiffany posted one photo while in Serbia's capital, captioning it "Greetings from Serbian" in Serbian.

Поздрав из Србије 👋🏻 A post shared by Tiffany Ariana Trump (@tiffanytrump) on Mar 12, 2019 at 5:25am PDT Mar 12, 2019 at 5:25am PDT

Boulos also posted a photo from Serbia during the same week on his personal Instagram account.

“If something is FOR YOU, all you have to do is BE YOU to receive it.” ✨ A post shared by Michael Boulos (@michaelboulos) on Mar 15, 2019 at 5:22am PDT Mar 15, 2019 at 5:22am PDT

Tiffany and Boulous met on vacation in Mykonos, Greece, last summer, according to Page Six, and she brought him to the White House for Thanksgiving last year.

Presidential travel costs have long been the target of political condemnation, with both Trump and former President Barack Obama being criticized for flight and lodging costs.

Before entering office, Trump tweeted criticisms of presidential travel.

According to a report from the Government Accountability Office published last month, Trump's frequent trips to Florida have cost taxpayers millions.

The report also found that Secret Service costs for Trump's adult sons, Eric and Donald Jr., reached nearly $400,000 for trips they took in January and February 2017, according to NPR.

A previous version of this article said Belgrade was in Siberia.