Norishige Kanai japanese astronaut
© ReutersNorishige Kanai, 41, left, claimed had grown three and a half inches in just three weeks in space
A Japanese astronaut has apologised for causing "fake news" after tweeting he had grown 9cm (3.5ins) since landing on the International Space Station.

Norishige Kanai, 41, today hastily corrected his initial claim by admitting he has actually only grown 2cm.

Tweeting Wednesday, he admitted: "Although it was a measurement error, it seems that it has become a serious topic. I am very sorry for the terrible fake news".

The first time astronaut did not explain why he made the initial claim but added he was glad he would be able to return to earth in the Soyuz spacecraft - which has a height limit.

His initial claim - which he called a "serious report" - was carried by news organisations around the world including the BBC, Washington Post and the Sun online.

ISS Japanese astronaut Norishige Kanai
Norishige Kanai is on board the International Space Station 250 miles above Earth
Dozens of experts were also called upon to explain his claimed growth.

It is very common for astronauts to grow between 2cm and 5cm while in space as the vertebrae in their spine stretch out due to the lack of gravity.

Kania hit the news after saying he feared he might not be able to fit in the Soyuz spacecraft due to bring him back in June.

The flight engineer said: "We had our bodies measured after reaching space, and wow, wow, wow, I had actually grown as much as 9cm! I grew like some plant in just three weeks.