India has declared one day of state mourning on Sunday as a mark of respect to Britain's Queen Elizabeth-II who breathed her last on Thursday.

"Her Majesty Queen Elizabeth II, United Kingdom of Great Britain and Northern Ireland, passed away on September 8, 2022. As a mark of respect to the departed dignitary, the government of India has decided that there will be one-day state mourning on September 11 throughout India," an official statement said.

The national flag will be flown at half-mast on the day of mourning throughout India on all buildings where the national flag is flown regularly and there will be no official entertainment on the day, it said.

President Droupadi Murmu, Vice President Jagdeep Dhankhar and Prime Minister Narendra Modi have expressed condolences at the demise of Queen Elizabeth II.

"In their messages, they noted that she was a stalwart of our times; a compassionate personality and provided inspiring leadership to her nation and people," a statement from the Ministry of External Affairs said.

The British High Commission has opened a book of condolence at the High Commissioner's residence here for people wishing to pay their respects.