The Big Bang Theory star Jim Parsons has dismissed rumours suggesting he is secretly engaged to his long-term partner.

The actor has been dating Todd Spiewak for 11 years and he has long been open about his views on marriage, insisting he is not "that enthusiastic" about tying the knot.

A report published in America's National Enquirer tabloid last week (ends17Aug14) suggested Parsons and Spiewak are secretly engaged and planning to exchange vows, and the actor has now spoken out to clarify his relationship status.

Parsons has posed a picture on showing the couple together in 2003, and he insists they are not planning to wed anytime soon.

He writes in the caption, "Me and Todd in 2003. Still very happy today... And Not engaged! #justFyi (for your information) #NationalEnquirerMakesS**tUp #duh (sic)."