The President spoke during a condolence visit to the British High Commissioner to Nigeria, Catriona Laing.
The late Queen Elizabeth of Britain backed Nigeria during the bloody Nigeria-Biafra civil war that left many dead.
President Muhammadu Buhari made the revelation over the weekend while mourning the passing of the monarch.
He said the UK during the Civil War between 1967 and 1970 supported the unity of Nigeria, adding that the Queen visited the country twice before her demise.
The President spoke during a condolence visit to the British High Commissioner to Nigeria, Catriona Laing, at her residence in Abuja on Saturday. He was represented by the Secretary to the Government to the Federation, Boss Mustapha.
Buhari said, “We have maintained very close ties with the monarchy. She was a very gracious and elegant queen.For the purposes of remembrance, the fact is that 90 per cent of Nigerians do not know any monarch in the UK other than the queen. We welcome the new king and we look forward to a strong working relationship with the UK.
“They have been a very strong ally even in the midst of our difficult time during the Biafran war; they stood for the indivisibility of the Nigerian state, supported and ensured that we overcame that problem.
We are partnering to deal with the insurgency so that it doesn’t overwhelm us. They have always stood as a very strong ally.”
Buhari added, “The head of the commonwealth to which we belong. Not only that, she was the head of state for three years from 1960 to 1963 and when we became a republic she ceased to be.
We have had very close ties with the queen. She visited the country twice; first in 1953 when she spent about 20 days visiting different towns, and the second one was in 2003 during president Olusegun Obasanjo’s tenure.”