JINDO, South Korea - As the 156th body was pulled from waters where the ferry Sewol sank a week ago, relatives of the nearly 150 still missing pressed the government Wednesday to finish the grim task of recovery soon. But the work was reaching a new, more complicated phase, with an official saying divers must now rip through cabin walls to retrieve more victims.

Looming in the background is a sensitive issue: When to bring in the cranes and begin the salvage effort by cutting up and raising the submerged vessel. The government has warned that the work might eliminate air pockets that could be sustaining survivors, but for some relatives that is a long-lost hope.

"Now we think we have to deal with this realistically," said Pyun Yong-gi, whose 17-year-old daughter is among the missing.

"We don't want the bodies to decay further, so we want them to pull out the bodies as quickly as they can," Pyun said on Jindo island, where recovered bodies are taken for families to identify.

That view is not shared among all relatives of the missing, however. One of them, Jang Jong-ryul, was sensitive about the mere mention of the word "salvage" and said most families don't want to think about it.

The number of corpses recovered has risen sharply since the weekend, when divers battling strong currents and low visibility were finally able to enter the submerged vessel. But Koh Myung-seok, spokesman for the government-wide emergency task force, said the work is becoming more difficult, and divers must now break through cabin walls.

"The lounge is one big open space, so once in it we got our search done straight away. But in the case of the cabins, we will have to break down the walls in between because they are all compartments," Koh said.

The government has not said when it intends to begin the salvage effort, though it has said it will be considerate of families of the missing.

"Even if there is only one survivor," Koh said, "our government will do its best to rescue that person, and then we will salvage the ferry."

For some relatives of the missing, speed in recovering the dead is becoming more important than shrinking hopes that their loved ones might still be alive.

"I've seen the bodies and they are starting to smell. It inflicts a new wound for the parents to see the bodies decomposed," Pyun said.

He and other relatives have set a deadline of Thursday for the government to recover all the bodies, though he concedes they have no way to enforce it. "We are not the ones who are actually doing it, so we know that there is nothing we can do," Pyun said.

The victims of the April 16 disaster are overwhelmingly students of a single high school in Ansan, near Seoul. More than three-quarters of the 323 students are dead or missing, while nearly two-thirds of the other 153 people on board survived.

The funeral halls in Ansan are already full, Oh Sang-yoon of the task force center said in a statement. He said the center "is taking measures to accommodate additional bodies by placing mortuary refrigerators at the funeral halls in Ansan," and directing mourning families to funeral homes in nearby cities.

Twenty-two of the 29 members of the ferry's crew survived, and 11, including Capt. Lee Joon-seok, have been arrested or detained in connection with the investigation. Two of the crew were arrested Wednesday, senior prosecutor Ahn Sang-don said.

Ahn said an analysis of photos and video on the ship before its sinking showed the captain and other arrested crew members didn't rescue passengers, though it was their duty. Ahn said the crew members were at the ship's steering room or engine room together before fleeing the Sewol earlier than passengers.

The captain initially told passengers to stay in their cabins, and waited about half an hour to issue an evacuation order. He has said he waited because the current was strong, the water was cold and passengers could have drifted away before help arrived. But maritime experts said he could have ordered passengers to the deck - where they would have had a greater chance of survival - without telling them to abandon ship.

It was not the crew but a passenger who first alerted authorities that the boat was in distress, the coast guard confirmed Wednesday.

An emergency call was made 8:52 a.m. last Wednesday to the Jeonnam 119 fire department, which transferred the call to the Mokpo coast guard office, the coast guard said in an emailed statement. The ferry made its first distress call three minutes later.

Yonhap news agency reported that the caller was a student from Ansan, and remains missing.

The cause of the disaster is not yet known. Ahn said investigators are considering factors including wind, ocean currents, freight, modifications made to the ship and the fact that it turned just before it began listing.

Tracking data show that the ship made a 45-degree turn, and that it turned about 180 degrees in the course of about three minutes around the time the vessel began to list.

A maritime professor who spoke with the Sewol's third mate, who is among those arrested and was steering the ferry before it sank, said he suspects a problem with the steering gear caused the sinking.

Professor Kim Woo-Sook of Mokpo National Maritime University said he spoke to Park Han-gyeol, a former student, a Mokpo detention facility. He says she told him she ordered a helmsman to make just a 5-degree turn, but the steering gear turned too far and the helmsman could not turn it back.

Kim said the steering gear would not have been enough alone to capsize the ship, but he suspects it caused poorly secured freight to shift, making the vessel unbalanced. He said he told her he believes she didn't make any mistakes in steering the ship, but that was wrong to have followed the captain in escaping the ship without protecting the passengers.

Senior prosecutor Yang Jung-jin said government investigators have not confirmed problems in the steering gear of the Sewol.

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Kim reported from Mokpo, South Korea. Associated Press writers Youkyung Lee in Incheon, Jung-hee Oh and Kyeongmin Lee in Jindo, Chang Yong-jun in Ansan, and Foster Klug, Jung-yoon Choi and Leon Drouin-Keith in Seoul contributed to this report.