NEW YORK (Reuters) - The Illinois Department of Insurance has approved Aetna Inc's <AET.N> proposed $34 billion acquisition of Humana Inc <HUM.N> provided it is approved by the U.S. Department of Justice, according to an order dated June 23 posted on the department's website.

Aetna announced the deal last summer and it is under review by the Justice Department, which is looking at competition concerns around its combined Medicare Advantage business for older people and the disabled.

In Illinois, Medicare Advantage plans, in which private insurers manage a customer's health benefits for the government, have enough competition because members can always turn to the traditional Medicare program if they are not happy, the state Department of Insurance said in its June 23 order.

"We now have change of control approvals in 17 of the 20 states required and continue to cooperate with the Department of Justice on its review," Aetna spokesman T.J. Crawford said.

The company continues to expect the transaction to close in the second half of 2016, he said.

(This version of the story corrects first sentence to show that Illinois approval is conditional upon U.S. Justice Department approval, instead of that Illinois approval has no conditions)

(Reporting by Caroline Humer; Editing by Tom Brown)