Jennifer Lopez is reportedly taking legal action over reports her backing dancer and boyfriend Casper Smart was "caught" in a "gay sex club" and an exotic massage parlour.

The couple is threatening to sue after claiming the stories are completely untrue.

Their high-powered attorneys, Shawn Holley and Howard Weitzman, have teamed up and allegedly sent letters to American publications Star Magazine and In Touch, warning them the "reports" are "false, malicious and defamatory" and will cause "immense damage" to the couple's careers and reputations.

The reports include photographs of Casper outside a XXX peep show in New York City in July, Star magazine claims the shop is a "well-known cruising spot for gay men looking for instant hookups."

In Touch magazine claims Casper was "caught" with an "exotic masseuse" at Hell's Kitchen – which he is said to have visited for 10 minutes - the day before he helped host Jennifer’s 43rd birthday.

In their letters, the lawyers have each demanded the magazines print a full retraction, warning Casper and Jennifer will "immediately file a lawsuit" if the magazines fail to do so, according to website TMZ.com.