KUALA LUMPUR • Former Malaysian prime minister Mahathir Mohamad said he did not expect to be celebrating his 90th birthday, and hoped he could continue "resolving the problems in the country".

The statesman, who was born on July 10, 1925, turned 90 yesterday, and is still sprightly, telling the BBC that he rode horses just last week.

Tun Dr Mahathir has his "official" birthday - the one listed in his birth certificate - on Dec 20. He has never explained why he has a different date on his birth cert.

When asked by Malaysiakini news website what his birthday wish was, he said: "If I am still able to move, I hope to continue being active in resolving the problems in the country.

"I am grateful I am able to celebrate my 90th birthday. This is something I never expected."

He was at the Kuala Lumpur national mosque yesterday with two of his seven children - Kedah Menteri Besar Mukhriz Mahathir and businessman Mokhzani Mahathir - along with two grandchildren, Malaysiakini reported.

Dr Mahathir has been in the limelight in the last few months as the most strident critic of Prime Minister Najib Razak and of the 1Malaysia Development Berhad state investors, whose board of advisers is chaired by Datuk Seri Najib.

Dr Mahathir is Malaysia's longest serving prime minister, holding the position for 22 years, between 1981 and 2003.

Malaysiakini yesterday published an interview with Dr Mahathir's wife, Dr Siti Hasmah Mohamad Ali, who said she prayed for her husband's good health and for him to finally see some resolution to his long struggle in Malaysian politics.

"I also pray so that he can, at least, see his fight end," she said.

Dr Mahathir is vocal on national issues simply because "no one else wants to speak up", she added.