UPDATE 1-Argentina reaches accord to take over Aerolineas

(Updates with price undetermined, official comment, details)

BUENOS AIRES, July 17 (Reuters) - The Argentine government has reached an agreement to take over the troubled airline Aerolineas Argentinas from Spanish travel group Marsans, Transport Secretary Ricardo Jaime told reporters on Thursday.

The government will buy all of Marsans' shares in the country's biggest airline at a price not yet determined, Jaime said.

"We're going to start the due diligence process that will allow us to determine the value of the shares," he said in televised remarks.

This is the latest in a series of state takeovers in recent years -- including the postal system, the largest water company and a train company.

The government has also pressured some foreign companies to sell stakes in power and energy companies to Argentine business leaders seen as presidential allies.

Aerolineas and its sister airline Austral have been plagued by worker strikes and complaints about poor service. Their debt has surged to $890 million under state-controlled fares despite subsidized jet fuel.

Privately owned Marsans bought Aerolineas in 2001 when the company was bankrupt.

Union leaders praised the state takeover of the airlines, which operate 80 percent of domestic flights and employ some 9,000 people.

The main competitor is Chile's LAN Airlines LAN.SN (LFL.N). (Reporting by Cesar Illiano and Hilary Burke; Editing by Brian Moss)