Government spokesman Alfred Mutua said the country "can no longer sit and watch as Kenyans suffer in hospitals without medical attention because nurses and other medical staff are on strike".
"The names of the 25,000 nurses who are on strike have been removed from the pay roll. They are no longer employees of the government," Mutua said.
The health workers went on strike to protest the government's failure to implement a salary increase agreed last year when they also halted work to press for improved services in Kenya's mostly ill-equipped public hospitals.
Medical Services Minister Anyang Nyong'o announced Wednesday that the nurses would be sacked if they failed to return to work.
