Paul Manafort’s alleged misstatements to special counsel Robert Mueller’s investigators include comments about his personal business dealings and about his contacts with a former associate in Ukraine, say people familiar with the matter.

Those statements—among those described by Mr. Mueller as “lies” and Mr. Manafort as “truthful information” in a court filing Monday—are what led the special counsel this week to take the unusual step of ending the former Trump campaign chairman’s plea agreement 2½ months after it was reached, the people said.

The content of those statements don’t appear to be central to the allegations of Russian interference in the 2016 election that Mr. Mueller is investigating. It is unclear if prosecutors plan to accuse Mr. Manafort of additional lies.

But Mr. Mueller’s move to end the cooperation deal reflects more broadly a combative relationship that has developed between Mr. Manafort and Mr. Mueller’s investigators, as well as the special counsel’s conclusion that Mr. Manafort fell short of his cooperation agreement, court filings show.

Investigators alleged that Mr. Manafort made inaccurate statements in interviews with Mr. Mueller’s team about his communications with Konstantin Kilimnik, said the people familiar with the matter.