WASHINGTON (Reuters) - U.S. Republican presidential nominee Donald Trump's campaign criticized the Iran nuclear deal and Democrat Hillary Clinton's support for it after a Reuters report that said the United States and its negotiating partners agreed "in secret" to allow Iran to evade some restrictions.

Retired Lieutenant General Michael Flynn, a Trump foreign policy adviser, said in a statement that the report showed President Barack Obama "gave away the store" when the agreement was sealed last year.

"The deeply flawed nuclear deal Hillary Clinton secretly spearheaded with Iran looks worse and worse by the day," the statement said, referring to Clinton's role during Obama's first term as secretary of state.

Reuters was first to report on a think tank report earlier on Thursday based on information provided by several officials of governments involved in the negotiations.

(Reporting by Steve Holland; Editing by Jonathan Oatis)