PETALING JAYA (The Star/Asia News Network) - Malaysian Prime Minister Najib Razak's step-grandmother Puan Sri Siti Amirah was one of the 43 Malaysians who are believed to have perished when Malaysia Airlines (MAS) flight MH17 crashed in Ukraine on Thursday.

According to a family spokesman, Mdm Siti was travelling alone on her way back to Jogjakarta, Indonesia from Amsterdam and intended to transit at Kuala Lumpur International Airport.

She was 83 years old, and was once married to Tan Sri Mohammad Noah Omar as his second wife. Tan Sri Noah, who passed away in 1990, was Datuk Seri Najib's grandfather.

"She was a very, very nice lady. A kind-hearted, beautiful woman. She was a homemaker who looked after my grandfather very well. We called her ibu (mother)," family spokesman Datin Faridah Abdullah told The Star over the phone on Friday.

Dr Faridah, who is also the chairman of the Mohammad Noah Foundation, said Mdm Siti had travelled to Amsterdam to holiday with her only daughter from her first marriage.

She added that Mdm Siti's daughter, who could not be named at this point, was supposed to have followed her mother on her way back but couldn't get on the same flight as her.

Dr Faridah said that Mdm Siti - a native Indonesian - and her daughter were planning to spend Hari Raya Aidilfitri in Jogjakarta.

"She had her own family in Amsterdam, and would go there and come back off-and-on. She visited Malaysia very regularly and loved Malaysia," said Dr Faridah.