A subsidiary of US casino firm Caesars has filed for bankruptcy protection with debts of $18.4bn.

Caesars Entertainment Operating Company, which owns and operates most of Caesars' properties worldwide, said it intended to keep the casino-hotels running, despite the bankruptcy filing in Chicago.

It was reportedly made to stop three creditors trying to push the firm into involuntary bankruptcy. 

The division of Caesars Entertainment Corporation employs 36,000 people at 38 casino-hotels, including the flagship Caesars Palace on the Las Vegas Strip.

It had been negotiating with creditors and lenders on a reorganisation plan that would turn the division into a real estate investment trust - one to own properties and the other to lease properties - promising creditors cash or new debt.

There have been a string of casino-hotel closures in Las Vegas and Atlantic City as companies focused investment in the fast-growing markets in Asia amid slowing business in the US and Europe.

Caesars, which has lost money each year for the last five years, slashed its global workforce by 1% last year and closed properties in cities including London.

"They're going to have to become a little leaner," Chris Jones told the Las Vegas sun, an analyst for Union Gaming Group.

He added that he doesn't expect any more properties to shut down and expects the plan will free up Caesars to reinvest where it hasn't, including the gambling floor.