Incoming Greek finance minister Vassilis Rapanos was admitted in hospital on Friday, the government said, with unconfirmed reports saying the 65-year-old senior banker had fainted.
The chairman of leading Greek lender National Bank, Rapanos was taken to a private hospital in Athens, a government spokesman said, hours before he was expected to take his oath of office.
"The hospital will issue a statement," the spokesman told AFP.
The state-run Athens News Agency said Rapanos had run a high fever while at his office at National Bank ahead of his swearing-in ceremony.
A former economics professor who served in the economy ministry when Greece joined the euro in 2001, Rapanos was named finance minister on Thursday in a conservative-led coalition seeking to revise the country's bailout terms.
Newly-elected Prime Minister Antonis Samaras was briefly in another Athens hospital Friday after being diagnosed with a retinal detachment.
He returned to his office according to state television, but will be admitted on Saturday to undergo an operation.