Leighton Meester has splashed out $1.5 million on a palatial mansion in Los Angeles' San Fernando Valley.

The 'Gossip Girl' star's new 2,847 sq ft, single storey property comprises of four bedrooms and four and a half bathrooms with a black-bottomed pool, a pool bar and a separate adjacent cabana with changing rooms in the extensive grounds situated in the upscale Royal Oaks neighbourhood.

The home's four bedrooms divide up into a guest/staff suite, two generously sized secondary bedrooms-one with private entrance to the garden - and a master suite which includes a small sitting area, fireplace with glass tile surround, walk-in closet, and an attached bathroom with double-sink vanity, soaking tub, and separate glass-enclosed steam shower.

Leighton already owns an apartment in New York - where 'Gossip Girl' is filmed and reportedly angered residents on the same floor of her building block when she asked them to refrain from smoking in their own homes because she "develops a sore throat if she's exposed" to smoke.

A source said: "She asked everyone not to smoke because the smell comes under her door."