WILMINGTON, Delaware (Reuters) - A White House official on Sunday denied Iran's claim that Washington and Tehran had reached a prisoner exchange deal, and said the United States was committed to ensuring the release of Americans held in the Islamic Republic.

"The claims by Iranian officials that we reached an agreement to release American citizens wrongly detained by Iran are false," a White House National Security Council spokesman said.

"Unfortunately, Iranian officials will not hesitate to make things up, and the recent harsh allegations will lead to more grief for the families of Siamak Namazi, Imad Sharqi and Morad Tahbaz," he added, referring to three Iranian-American dual nationals being held in Iran.