Iran on Tuesday condemned a U.S. court's decision to sentence an Iranian national to five years in prison as "illegal and unacceptable," the satellite Press TV reported.

Addressing the reporters on Tuesday, Iran's Foreign Ministry spokesman Ramin Mehmanparast said that Tehran would make serious diplomatic efforts to secure the release of its national Amir- Hossein Ardebili.

"The information we have received about Mr. Ardebili shows that he is going to be condemned to time in prison in an illegal manner," Mehmanparast was quoted as saying by Press TV.

"We definitely disagree with that. This is illegal and we are trying our best to ensure that the court revokes this illegitimate verdict," he added.

Ardebili was sentenced in U.S. District Court in Wilmington, Delaware, on Monday to five years in prison after being snared in a global undercover investigation.

The 36-year-old Iranian national pleaded guilty last year to violating U.S. arms control laws by trying to purchase components for Iranian fighter planes and missile guidance systems.

Ardebili was captured in the Republic of Georgia in October 2007 and handed over to the U.S. government in January 2008.