'Gossip Girl' star Leighton Meester suing mother?

Gossip Girl Leighton Meester has reportedly begun legal action against her mother over claims she used money intended for her sick younger brother on cosmetic surgery instead.

According to TMZ, Leighton alleges her mother Constance Meester spent funds meant to pay for her son's medical expenses on various cosmetic procedures, botox treatments and hair extensions.

The lawsuit also refers to Constance's claim she had entered into an oral agreement with her daughter that Leighton would pay her a monthly allowance of $10,000 (£6,100).

Constance is said to have threatened to sue Leighton for a sum of $3 million ($1.8 million) if she refused to keep up the payments.

Leighton, who denies there was any such agreement, is asking the court to declare that there is no contract between her and her mother.

Earlier this year it was reported that Meester had begun dating Going the Distance star Justin Long.

Since starring on The CW drama Gossip Girl, Meester has gone on to feature in several films including teen thriller The Roommate and romantic comedy Monte Carlo opposite Selena Gomez and Katie Cassidy.

Watch Leighton Meester in the trailer for Monte Carlo below: