(Refiles to fix typo in headline)
By Ju-min Park and Hyunjoo Jin
SEOUL Aug 19 (Reuters) - South Korean ruling and opposition party leaders agreed on Tuesday on legislation to investigate April's Sewol ferry disaster more deeply, but a spokesman for families of the victims said they would oppose the bill.
The Sewol, overloaded and travelling too fast on a turn, capsized and sank on a routine journey on April 16, killing more than 300 people, most of them school children, prompting a backlash against the government of President Park Geun-hye over its handling of the disaster.
Family members of the victims and survivors have been calling for a more transparent investigation into the sinking of the ferry and subsequent rescue operation, which was widely criticised.
Tuesday's agreement had appeared to end a deadlock that had threatened to derail other legislation, but the opposition of family members could jeopardise the deal that still needs approval from legislative committees and the full parliament.
"We oppose it. Both parties, the ruling party and the opposition party, have not communicated with us or tried to explain what they are doing to help us understand," Yoo Gyoung-geun, who lost a daughter in the disaster and is a spokesman for the victims' families, told Reuters.
"Our families have been hurt a lot and some of us thought politicians are just using us for their election campaign," Yoo said, referring to by-elections last month.
The current parliamentary session was due to end on Tuesday, but a special session was likely to be convened on Aug. 25, Yonhap News Agency said.
The two main parties had been at loggerheads over specifics of the bill, and the main opposition party had threatened to boycott the passage of other time-sensitive legislation until the dispute was resolved.
The main point of contention has been the makeup of a committee to choose a special prosecutor. The families had wanted an independent team of experts, half of them to be named by the families, with the right to prosecute.
Under Tuesday's agreement, a panel of seven members, two of whom must be approved by the family members, would choose two potential prosecutors, from which the president would pick one. (Additional reporting by James Pearson; Writing by Tony Munroe; Editing by Nick Macfie)