More than 30,000 workers began a strike on Friday
"President Ahtisaari is doing well given the circumstances," it said.
On Saturday, Ahtisaari's 83-year-old wife Eeva also tested positive for the infection.
Finnish health authorities have confirmed 700 cases of Covid-19, and one death, although not all suspected infections are being tested.
Officials have said the real number of people with the virus could be 30 times higher.
Schools in Finland are shut to children over the age of 10, and the country's borders have been closed to all visitors who are not residents or citizens.
Prime Minister Sanna Marin said on Monday that further restrictions on movement would be announced imminently.
More than 30,000 workers began a strike on Friday
GAYA aims to build a blockchain system to support entrepreneurial projects in several sectors
The authority also urged people to follow all safety instructions issued by the authority on ground
The famous work was stolen from a London gallery on September 8
With fast printing and ink tanks that provide over 7,000 pages on a single fill, the Epson EcoTank L5590 combines peace of mind with print performance
Hamas vows Israel 'will not enjoy security' unless it ends its offensive in Gaza, praises Yemen rebels for their rare missile attack on Israel
Torrential rain has lashed conflict-racked Myanmar in the wake of the typhoon which smashed into Vietnam on September 7
The Dragon spacecraft landed in the ocean at 3.37am, a webcast of the splashdown showed, with a recovery team deploying in the pre-dawn darkness to retrieve the capsule and crew