Mathew Barrett arrived in Islamabad earlier this month and was cleared at the airport. Later, his name was found in the blacklist and he was arrested from a guest house here.
A case was registered against him for violating immigration laws.
After initial hearing, a court ordered two days ago that he should be deported.
“He was taken to Lahore from Islamabad last night and put on flight PK-711 for the United States,” an official said.
Barrett was blacklisted and deported in 2011 after he was arrested from nearby a nuclear site in Punjab province.
However, he got a visa from Pakistani consulate at Houston and landed in Pakistan.
Pakistan has launched an internal probe against the officers who granted the visa and entry to the blacklisted man. It is believed that Pakistan was under pressure from the US to show leniency towards Barrett.
PTI