The former husband and the former boyfriend of the woman on whom the hit film Erin Brockovich was based have been arrested for trying to extort more than $300,000 (£190,400) from her. They had allegedly threatened to make false claims to the American tabloids that Ms Brockovich, played by Julia Roberts in the film, had been a bad mother and had had an affair with her boss, the lawyer Ed Masry.

The two men and a lawyer representing them were arrested in Thousand Oaks, California after a sting worthy of a movie itself. Shawn Brown, 38, Ms Brockovich's former husband and her ex-boyfriend Jorg Halaby, 46, who is portrayed sympathetically in the film, were allegedly unhappy that they had not profited substantially from the hit movie.

It is based on the true story of Ms Brockovich, 39, an unqualified legal worker who took on the utility company Pacific Gas & Electric and won a £211m settlement for 650 California residents affected by a poisoned water supply. She was given a £1.3m fee.

According to the charges, John Reiner, a lawyer representing the two, called Mr Masry earlier this month to say that Mr Brown would give interviews suggesting that Ms Brockovich had been a bad mother and had had a sexual relationship with Mr Masry; allegations denied by Ms Brockovich and Mr Masry.

The two men and their lawyer were then invited to a meeting with mother-of-three Ms Brockovich, Mr Masry and a lawyer, Cathleen Drury, who is representing Ms Brockovich in a child custody case. Ms Drury had already contacted the FBI and a hidden camera was installed in her office.

The cameras ran as the two men made their claims and signed a silence agreement in exchange for £19,000 for Mr Halaby and £178,000 for Mr Brown. The trio have been charged with extortion.

Ms Brockovich said Mr Halaby had already been paid by the film's makers, Universal, for being portrayed in the film. Mr Brown, who is not featured in the film, received nothing.