NEW YORK - Fitch Ratings put AIG's aircraft leasing unit, International Lease Finance Corp. on negative rating watch on Friday, citing concerns whether the company could be sold in a way that would keep its ratings at investment grade level.

The placement of ILFC's ratings on Rating Watch Negative essentially reflects heightened concerns and uncertainty surrounding efforts to execute a sale of the company that would preserve its investment-grade capital structure, Fitch said in a statement. The rating watch went to negative from evolving.

Fitch downgraded ILFC's Preferred Stock rating to B from BB.

Approximately $19 billion of debt is affected by these actions, the rating agency said.

Because of the time it is taking AIG to divest ILFC and also due to on-going difficult capital market conditions, Fitch now believes that such a scenario is unlikely to occur, the rating agency said.

ILFC's senior unsecured debt is rated BBB.

(Reporting by John Parry; Editing by Andrew Hay)