Meghan Markle's memory of a phone call from Oprah in 2018 makes it sound like the then duchess-to-be was being held captive by the Royal Family.

O just released another clip from her highly anticipated interview with Meghan and Prince Harry ... where Oprah recalls calling Meghan months before her royal wedding to request an interview and being politely turned down. Back then, Meghan said the timing wasn't right, but now she says that was an excuse forced on her.

The reality was, according to Meghan ... "I wasn't even allowed to have that conversation with you personally, right? There had to be people from the comm., sitting there."

Meghan says the timing is right now, though, because she and Harry finally have the ability to make their own choices.

She also suggests that people can't imagine what it was like to leave her independent life and enter the "construct" of the monarchy.

As we reported ... the Duke and Duchess' interview with Oprah has promised to be "shocking," and the couple's essentially declared war against Queen Elizabeth and Buckingham Palace by accusing them of spreading "falsehoods" about them.

Get your popcorn ready!