VICTORIA'S deputy premier Peter Ryan is in hospital undergoing tests for a possible blood infection.

A spokesperson for Mr Ryan said an appointment had not been made to replace the deputy premier while he was in hospital.

"Mr Ryan has been advised to remain in hospital while these tests continue," the spokesperson said in a statement.

"Acting arrangements will be put in place to cover Mr Ryan's ministerial responsibilities."

Mr Ryan is also the minister for police and emergency services, bushfire response and regional development.

It is not known how long Mr Ryan will be absent, but his diary had been cleared until Tuesday, a spokesman said.