A Keadilan leader has expressed surprise at former coalition partner DAP's decision to contest in the Oct 12 Gaya parliamentary seat by-election, turning it into a three-cornered fight.

Party supreme council member Cheah Kah Peng said DAP had spurned Keadilan's offer to national chairperson Lim Kit Siang to represent the opposition in the contest for the Sabah seat.

"We are equally surprise of DAP's entry into the by-election as we have made our intention (to contest) long ago," said Cheah, who is also Penang Keadilan deputy chief.