Separatist parties are seen winning a solid absolute majority of seats in Catalonia's regional parliament, an exit poll showed on Sunday, potentially setting the region on a collision course with Spain's central government over independence.

The main secessionist group "Junts pel Si" (Together for Yes) would get between 63 and 66 seats in the 135-strong assembly, while smaller leftist party CUP would secure another 11 to 13 seats, according to the poll released by local broadcaster TV3, the largest carried out. 

They would jointly obtain 49.8 percent of the vote.

Both have said that if they win a majority they would unilaterally declare independence within 18 months, something the central government in Madrid says it would block in court because the Spanish constitution does not allow it.

(Reporting by Julien Toyer; Editing by Elisabeth O'Leary)