The country's rival parties spoke in rare unison Thursday, calling for the safe recovery of a passenger ferry that sank nearly three years ago.

But the pro-government and opposition blocs still differ about what should come next.

The liberal Democratic Party, formerly the largest opposition party here, urged efforts to identify what caused the tragic sinking of the ship, Sewol, on April 16, 2014, and the death of 304 passengers, mostly high school students.

"With all the rest of the nation, I sincerely hope the ship will be safely recovered and all missing persons will return to their families," said Moon Jae-in, referring to nine missing passengers from the ship.

Moon, a former chief of the Democratic Party, is now seeking the party's nomination for the May 9 presidential election. He is currently facing three other contenders in a party primary.

"If I am elected, I will launch a second special investigation panel and identify every little piece of truth behind the sinking of the Sewol," he said.

An Hee-jung, South Chungcheong Province governor and one of four contenders in the Democratic Party primary, was in the vicinity of the accident site to meet with the families of those missing and killed in the tragic accident.

"I will do my utmost to thoroughly determine the cause of the accident while also paying attention to the recovery of those who remain missing," he was quoted as telling the families.

Seongnam City Mayor Lee Jae-myung, also a Democratic Party contender, expressed hope that the physical recovery of the ship will be the start of an emotional recovery for many family members of victims.

"I wish the recovery of the Sewol will be the start of identifying the truth behind the tragedy," he said at a press conference in Gwangju, some 300 kilometers southwest of Seoul.

Officials from the former ruling Liberty Korea Party and the conservative Bareun Party also expressed hope for a safe and successful salvage of the ship.

"The government and the political circles must do their utmost to find out the cause of the accident and enhance the country's safety measures to make sure such a tragedy will never occur again," In Myung-jin, the interim head of the former ruling party, said.

However, the chief of the former ruling party apparently sought to redirect people's attention from the thorny issue which, at least in part, may have contributed to the parliamentary impeachment of former President Park Geun-hye, which led to her removal from office on March 10.

In addition to a series of corruption allegations, the former president faced strong public anger over her government's botched response to the tragic sinking which left 304 dead.

Referring to the sinking of a Korean warship, the Cheonan, by a torpedo attack from a North Korean submarine seven years ago on Sunday, the interim head of the Liberty Korea Party said security cannot and will not be ensured by one single party.

"The attempt by some political figures to continue such a consuming debate does not ensure the people's safety or the country's security," he said.

The Bareun Party, which broke away from the former ruling party, has designated the entire week for the commemoration of the 2010 sinking of the Cheonan, which left 46 young South Korean sailors dead.

Rep. Yoo Seong-min, seeking to run for president on the ticket of the conservative party, expressed opposition to politicizing the tragic incidents.

"I wish the Barun Party will be a party that can embrace and console all, and never use either the Cheonan or Sewol accident for political gain," he said.

Yoo served as a floor leader of the former ruling party. He is currently facing Gyeonggi Province Gov. Nam Kyung-pil in the Bareun Party's presidential nomination race. (Yonhap)