Image copyright Reuters Image caption The couple, both 26, met at a restaurant while studying at university in 2012

Japan's Princess Mako is postponing her wedding to her college sweetheart until 2020 due to a lack of time to plan the nuptials, media reports say.

The 26-year-old granddaughter of Emperor Akihito was scheduled to marry law firm worker Kei Komuro in November.

The couple announced the delay was due to a lack of time to make "sufficient preparations", Jiji Press reported.

Their decision accounted for the imperial family's busy plans next year, including the emperor's abdication.

"I am very sorry for causing a big trouble and extra burden to those who have sincerely helped our wedding," AFP news agency quoted the princess as saying.

She will lose her title when she marries Mr Komuro, a commoner.

An imperial household spokesperson confirmed that the couple, who met in 2012, still intend to tie the knot after important ceremonies related to the emperor's abdication and the crown prince's accession.

The household also denied the postponement was related to a recent magazine article about alleged financial problems involving Mr Komuro's mother, according to Jiji.

In April 2019, Emperor Akihito, 84, will become the first Japanese emperor to step down from the Chrysanthemum Throne in more than 200 years.

His eldest son and uncle to Princess Mako, 57-year-old Crown Prince Naruhito, will succeed him.