The Japanese government has executed a man who went on a stabbing rampage in 2008.

Tomohiro Kato, who was 25 at the time, ran a truck into a busy Tokyo shopping district on June 8, 2008, before going on a stabbing rampage, killing seven people and injuring 10.

Justice Minister Yoshihisa Furukawa told reporters Kato, 39, was hanged at the Tokyo detention centre on Tuesday.

Kato was sentenced to death in 2011, a decision that was upheld by Japan's top court in 2015.

Japan has maintained the death penalty despite growing international criticism.

Mr Furukawa said capital punishment was a justified response to continuing heinous and violent crime and scrapping it wasn't appropriate at this point.

Mr Furukawa said Kato had thoroughly prepared to commit the mass killings — "an atrocious act that led to extremely serious consequences and had a major impact on society."

Kato told police: "I came to Akihabara to kill people. It didn't matter who I'd kill."

He was arrested on the spot shortly after the attacks, in which he rammed the rented two-tonne truck into pedestrians before randomly stabbing people.

Police said he documented his deadly journey to Akihabara on Internet bulletin boards, typing messages on a mobile phone from behind the wheel of the truck and complaining of his unstable job and his loneliness.

While awaiting trial, he wrote to a 56-year-old taxi driver whom he injured in the stabbing spree, expressing his remorse.

The attack was Japan's worst mass killing in seven years.

Mr Furukawa denied Tuesday's hanging was related to the shooting death of former Prime Minister Shinzo Abe earlier this month, which shocked the nation known for strict gun controls and low crime rate.

Tuesday's hanging was the second under the government of Prime Minister Fumio Kishida, who took office in October.

Japan now has 107 people on death row, including 61 seeking retrials, Mr Furukawa said.

AFP/AP/Reuters