GT3 cars will be allowed to compete in the European Le Mans Series next year.
The machines will compete in the GTC class, which was introduced this year for cars of Porsche Carrera Cup/Ferrari 430 Challenge-level specification, but failed to attract any entrants.
GT3 has become the world's most popular category of GT racing since its inception in 2006, and now forms the basis of most high-level domestic championships.
The ELMS, which recently announced a five-round calendar for 2013, will comprise five classes next year. LMP2 and LMPC machinery will make up the prototype field while GTE, split into the usual Pro and Am sections, will partner GTC.
ELMS CEO Gerard Neveu said: "We already have several teams wishing to run cars in the GTC class and the 2013 ELMS grid will have a positive boost as a result of this decision."