Japan’s Princess Mako has postponed her marriage to her university sweetheart, saying in a surprise announcement that their wedding plans had been “rushed”.

The country’s imperial household said the ceremony, originally planned for November, would be delayed until 2020 to allow the couple “to think about marriage more deeply” and “make sufficient preparations”.

The announcement prompted speculation, denied by the household, that the decision was related to criticism in Japanese tabloids of her fiance Kei Komuro’s family background.

Mako, Emperor Akihito’s oldest grandchild, will lose her title when she marries Mr Komuro a commoner. The couple, both 26, met at Tokyo’s International Christian University in 2012 and excitement swept the country when they announced their engagement last year.

In a statement published in Japanese media, Mako said: “We have come to realise the lack of time to make sufficient preparations for various events leading up to our marriage this autumn and our life afterwards. We believe that we have rushed various things too much.

“I wish to think about marriage more deeply and concretely and give sufficient time to prepare our marriage and for after the marriage.”

An Imperial House Agency spokesman said the postponement of the wedding decision was not related to tabloid magazine reports about disputes between Mr Komuro’s mother and her former partner. The row reportedly centred on money his mother borrowed to cover her son’s tuition fees and allegedly never paid back.

She said Akihito and his wife, Empress Michiko, expressed respect for their decision when she reported it to them.

No new date has been set for the wedding, which will now take place the year after the emperor’s abdication. Akihito, 84, will become the first Japanese emperor to step down in more than 200 years when he abdicates on April 30, 2019. His eldest son, Crown Prince Naruhito, will take his place on the Chrysanthemum Throne the next day.

The palace requested 150 million yen (£984,000) as part of its 2018 budget to cover the costs of Mako leaving the royal family.