WASHINGTON – The White House severely restricted distribution of memos detailing President Donald Trump's calls with foreign leaders, including Russia's Vladimir Putin and Saudi Arabia's Mohammed bin Salman, in an effort to curtail the kind of leaks about such private conversations that had embarrassed him early in his tenure, a former White House official said.

The clampdown was not an attempt to conceal improper discussions but rather keep distribution about the substance of the calls to a minimum in light of the leaked transcripts from the summer of 2017, according to the official, who was not authorized to publicly talk about the process and spoke on condition of anonymity. At that time, Trump was enraged by leaks that disclosed tough conversations with the leaders of Mexico and Australia on paying for the border wall and abiding by an Obama administration deal on asylum-seekers.

The White House's handling of Trump's calls with foreign leaders is now at the heart of House Democrats' impeachment inquiry. A whistleblower alleges the White House tried to cover up Trump's July 25 phone call with Ukraine's new president in which Trump asked Volodymyr Zelenskiy for help investigating Trump's Democratic rival Joe Biden, as well as other calls.

The former White House official confirmed there was an effort to limit access to Trump's calls, but offered an alternative explanation: The White House was trying to limit leaks of private conversations. CNN first reported on the White House effort.

The whistleblower is accusing Trump of using his office to "solicit interference from a foreign country" to help himself in next year's U.S. election.

The call came days after Trump ordered a freeze to some military assistance for Ukraine, Trump prodded Zelenskiy to dig for potentially damaging material on Biden, the former vice president who is a leading contender for the 2020 Democratic presidential nomination, and volunteered the assistance of both his personal lawyer, Rudy Giuliani, and his attorney general, William Barr.

The White House has acknowledged that a record of that call was sealed away in a highly classified system at the direction of Trump's National Security Council lawyers.

The former official noted that even some of Trump's calls with American allies were restricted due to the classified matters that arise during the discussions.

After the disclosures about Trump's calls to the Australian and Mexican leaders, a White House adviser raised the possibility of lie detector tests for the small number of people in the West Wing and elsewhere with access to transcripts of Trump's phone calls.