In this Tuesday, July 10, 2018, file photo, President Donald Trump is joined by Gordon Sondland, the U.S. ambassador to the European Union.

Sondland was directed early Tuesday by the State Department not to show up for a closed-door hearing before the House Intelligence, Oversight and Foreign Affairs committees, said Sondland's counsel, Robert Luskin, in a statement to NBC News.

House Intelligence Committee Chairman Adam Schiff, D-Calif., said that the State Department had also blocked Sondland from sharing documents related to the impeachment inquiry. Schiff called the White House's moves "further acts of obstruction of a coequal branch of government."

The subpoena came hours after the White House ordered Sondland, the U.S. ambassador to the European Union, not to appear for a scheduled deposition Tuesday with the House panels.

House Democratic leaders on Tuesday subpoenaed top diplomat Gordon Sondland to testify at a deposition and hand over a slew of documents related to their impeachment inquiry into President Donald Trump.

Luskin said Sondland had "previously agreed to appear voluntarily today, without the need for a subpoena, in order to answer the Committee's questions on an expedited basis." But "as the sitting U.S. Ambassador to the EU and employee of the State Department, Ambassador Sondland is required to follow the Department's direction."

House Democrats have warned the Trump administration that any attempts to interfere with the impeachment inquiry will be viewed as evidence of obstruction.

Sondland's text messages with other U.S. diplomats were released last week after they were given to those House panels by former U.S. special envoy to Ukraine Kurt Volker during his own deposition. In a Sept. 9 exchange, Bill Taylor, a senior U.S. diplomat in Ukraine, told Sondland: "I think it's crazy to withhold security assistance for help with a political campaign."

Sondland responded: "Bill, I believe you are incorrect about President Trump's intentions. The President has been crystal clear no quid pro quo's of any kind. The President is trying to evaluate whether Ukraine is truly going to adopt the transparency and reforms that President Zelensky promised during his campaign."

Click here to read those texts.

Trump, in a pair of tweets, said Tuesday that he would "love" to send Sondland to testify, "but unfortunately he would be testifying before a totally compromised kangaroo court, where Republican's rights have been taken away, and true facts are not allowed out for the public to see."

Trump TWEETS

Luskin said in his statement that Sondland "is profoundly disappointed that he will not be able to testify today."

"Ambassador Sondland traveled to Washington from Brussels in order to prepare for his testimony and to be available to answer the Committee's questions," Luskin said, adding that his client "believes strongly that he acted at all times in the best interests of the United States, and he stands ready to answer the Committee's questions fully and truthfully."

The New York Times first reported that the Trump administration made the move to block Sondland from speaking before the Democrat-led committees, which are in the midst of an impeachment probe sparked by Trump's July 25 phone call with Ukraine President Volodymyr Zelensky.