Kumaratunga was sending letters to the ministers informing them of their formal removal after the dissolution of parliament at the weekend, which turned the government into a caretaker body, a spokesman said.
A senior member of Kumaratunga's party, Maithripala Sirisena, said the president was also contemplating reducing the number of ministers in the caretaker cabinet, but there was no announcement on the sacking of any cabinet ministers.
Kumaratunga dissolved parliament on Saturday, nearly four years before its six-year term was up.
The political crisis erupted following her power struggle with Prime Minister Ranil Wickremesinghe who is from a rival party.
The sacking of Sri Lanka's parliament by the president has hit the country's economy too. A World Bank official warned on Wednesday the development could hold up at least $176 million in the bank's aid to the island, whose economy is headed for a serious slowdown.
Poverty reduction support credits amounting to $125 million were due to be taken up for approval by the World Bank board, but this would now be delayed, said the bank's country director there, Peter Harrold.
"Our macro programme will have to wait until the elections are
over," Harrold told AFP.