* Rescue efforts continue as winds, waves pick up
* About 290 people still missing, many of them teenagers
* Parents blame government, say not enough help and information (Adds captain subject to criminal investigation, other details)
By Narae Kim
JINDO, South Korea, April 17 (Reuters) - Rescuers fought rising wind, strong waves and murky water on Thursday as they searched for hundreds of people, most of them teenaged schoolchildren, missing after a South Korean ferry capsized more than 24 hours ago.
Coastguard, navy and some private divers were operating in waters at the site of the accident, about 20 km (12 miles) off the country's southwestern coast. Earlier, rescue teams hammered on the hull of the upturned vessel, hoping for a response from anyone trapped inside, but did not hear anything, media said.
The vessel, carrying 475 passengers and crew, capsized on Wednesday during a journey from the port of Incheon to the holiday island of Jeju. Nine people were found dead and 179 were rescued, according to the South Korean government, leaving 287 unaccounted for and possibly still trapped in the vessel.
One parent, Park Yung-suk, told Reuters at the port of Jindo, where rescue efforts are centred, that she had seen the body of her teenage daughter's teacher brought ashore.
"If I could teach myself to dive, I would jump in the water and try to find my daughter," she said. Her daughter was one of 340 children and teachers from the Danwon High School in Ansan, a Seoul suburb, on board the vessel.
The captain of the ship, Lee Joon-seok, 69, faces a criminal investigation, a coastguard official said, amid unconfirmed reports that he was one of the first to jump to safety from the stricken vessel.
The official did not elaborate, but media said the captain faced possible charges of negligence leading to death and violating a law that governs the conduct of shipping crew.
Many survivors told media Lee was one of the first to be rescued although no one had actually seen him leave the ship. The coastguard and the ferry operator declined comment.
Although the water at the site of the accident is relatively shallow at less than 50 metres (165 feet) depth, it is still highly dangerous for the 150 or so divers who are working as fast as they can, experts said. Time was running out to find any survivors who may be trapped inside, they said.
"The chances of finding people in there are not zero," said David Jardine-Smith, secretary of the International Maritime Rescue Federation, adding however that conditions were extremely difficult.
"There is a lot of water current and silt in the water which means visibility is very poor and the divers are basically feeling their way around."
The government said it was not giving up on the possibility of finding survivors.
"We carried out underwater searches five times from midnight until early in the morning, but the strong currents and murky waters pose big obstacles," Kang Byung-kyu, a minister for public security, told a news conference in the capital, Seoul.
There is no official explanation for the sinking, although the government has launched a formal inquiry. The ship, built in Japan 20 years ago, was following a well travelled route. Although the wider area has rock hazards and shallow waters, they were not in the immediate vicinity of its usual path.
The ferry was found to have three safety deficiencies in 2012, including one related to navigation, but passed subsequent safety checks in 2013 and 2014, according to international and Korean shipping records.
The ferry's capacity was increased to more than 900 people from 800 when it was imported from Japan in late 2012, shipping sources said, but the expansion passed all safety tests. The ship, its passengers and cargoes are all under two separate insurances, industry sources said.
State broadcaster YTN quoted investigation officials as saying the ship was off its usual course and had been hit by a veering wind which caused containers stacked on deck to shift.
The vessel was listing heavily to one side on Wednesday as passengers wearing life jackets scrambled into the sea and waiting rescue boats, according to television footage.
It sank in about two hours and witnesses and media showed that just two life rafts from the ship successfully inflated and launched. Earlier reports said just one had inflated.
The operator, Chonghaejin Marine Co Ltd, based in Incheon, issued a brief statement via media apologising for the accident but has made no further comment. The unlisted operator, which owns four other vessels, reported an operating loss of 785 million won ($756,000) last year.
A company called Web Solus is providing an underwater drone free of charge to examine the interior of the vessel where survivors could be located.
"Families and rescuers have been just looking at the surface of the sea. We have to move fast and at least see some of the vessel under the water," Ko Se-jin, the operator, told Reuters.
Among those on the ship were two Chinese citizens, according to Chinese media, one Russian and two Filipinos. The Philippines citizens were safe, according to Korean authorities, but the whereabouts of the others were not known.
Hope rests on whether the passengers inside would have been able to find air pockets, Jardine-Smith, the rescue expert, said. "It is not impossible that people have survived, but, tragically, it's very unlikely that many will have done." ($1 = 1037.6500 Korean Won) (Additional reporting by Jack Kim, Ju-Min Park, Choonsik Yoo, Meeyoung Cho, Kahyun Kang and James Pearson in SEOUL, Jungmin Jang in MOKPO, South Korea, and Jonathan Saul in LONDON; Writing by Raju Gopalakrishnan; Editing by Robert Birsel)