Eleven more bodies were recovered on Sunday, taking the death toll to 80.
France's ambassador in the country was one high-profile donor who donated blood and urged others to follow suit.
The passenger train was travelling from Yaounde, the capital, to the port city of Douala when carriages flipped over at high speed.
President Paul Biya told state TV that victims' [medical] costs would be paid for by the state.
He said an "in-depth inquiry" into the causes of the accident had been ordered.
A day of mourning is being observed in the country with flags flying at half-mast, the BBC Richard Onanena in Yaounde says.
Efforts are still underway at the central hospital of Yaounde to identify some of the dead, our correspondent adds.
The wounded are being treated in hospitals in Yaounde and Douala, the two main
cities in the country.
To cope with the emergency, at least 20,000 sachets of blood are needed, which officials hope to secure through the appeal.
"This is unprecedented and it came suddenly. Treating the wounded involves a considerable number of physicians," Tetani Ekwe, vice-chairman of the National Order of Physicians, told BBC Afrique.
"We can't afford to pay for the blood we need, so citizens have to donate their blood," Mr Ekwe added.
The National Order of Physicians has called on all medical professionals to go and offer their help at the hospitals where the wounded have been taken