Iran's top leader has pardoned a controversial Iranian-Canadian blogger more than 11 years before the end of his prison term, the semi-official ISNA news reported on Thursday.

The report said authorities informed Hossein Derakhshan about his amnesty late Wednesday when he returned to Tehran's Evin prison from one of his occasional leaves.

The report did not elaborate on the reason for Derakhshan's pardon by Supreme Leader Ayatollah Ali Khamenei, who has final say on all state matters.

However in the past, Derakhshan's parents have reportedly sent letters to Khamenei seeking their son's pardon.

Derakhshan, founder of one of the first Farsi-language blogs, was first detained in 2008. In 2010, a court sentenced him to more than 19 1/2 years in prison for his writings, the term later dropped to 17 years.

Derakhshan, now 39, helped ignite blogging in Iran by posting online simple instructions on how to create sites in Farsi in 2001. The subsequent flourishing of blogs by Iranians at home and abroad gave the country's reform movement a crucial online platform.

Writing from Canada, Derakhshan was initially a critic of Iran's clerical leadership. He visited Isrnkael, Iran's archenemy, in 2006 saying he wanted to act as a bridge between the two peoples.

Derakhshan was convicted on charges of cooperation with hostile countries -- a reference to the Israel visit -- spreading propaganda against the ruling establishment, promotion of counter-revolutionary groups and insulting Islamic thought and religious figures.

But he later became a vocal supporter of former hard-line President Mahmoud Ahmadinejad, praising him for standing up to the West and criticizing regime opponents.