The Chinese foreign ministry on Wednesday insisted on calling Chinese President Xi Jinping's trip to Britain in 2015 "a great success," in response to the question on Queen Elizabeth II's comment on Chinese officials being "rude" to the UK ambassador.

"President Xi Jinping's state visit to the UK last October was a great success, thanks to the enormous efforts made by the teams of the two sides. Both China and the UK agree on that. The two sides have made arduous efforts to ensure its success. China and the UK also agree on that," Lu Kang, Chinese foreign ministry spokesperson, said at a press conference on Wednesday.

In response to a follow-up question on bilateral relations, the spokesperson pointed out that Xi's State visit to the UK last October ushered in a new phase of building a "golden era" for bilateral relations.

"This was also echoed by the British side," Lu added.

In footage broadcast by the BBC, the queen is seen at a garden party in Buckingham Palace on Tuesday, meeting senior police officer Lucy D'Orsi, who is introduced by an official as having been in charge of security during Xi's visit in October last year.

D'Orsi then described her dealings with Chinese officials as "quite a testing time" and recounts that at one point they had walked out of a meeting and told her "the trip was off," Reuters reported.

The queen said, "They were very rude to the ambassador."

A spokeswoman for the queen said, "We do not comment on the queen's private conversations. However, the Chinese state visit was extremely successful and all parties worked closely to ensure it proceeded smoothly," according to Reuters.

Under her constitutional role, the 90-year-old monarch never makes any politically or diplomatically sensitive comments in public, and it is rare for the content of her private conversations to be revealed, Reuters said.

Xi's visit to the UK marked the first State visit to the country by a Chinese president since former Chinese president Hu Jintao's visit in 2005.

The two countries signed a series of mutual investment agreements worth $61.6 billion.