11:25AM EST: [UPDATE BELOW] A South Korean naval vessel with more than 100 aboard was sinking on Friday in waters near North Korea and Seoul was investigating whether it was hit in a torpedo attack by the North, South Korean media said.

Broadcaster SBS said many South Korean sailors on the stricken vessel were feared dead.

South Korea’s YTN TV network said the government was investigating whether the sinking was due to a torpedo attack by the North, and Yonhap news agency said the Seoul government had convened an emergency meeting of security-related ministers.

Yonhap also reported a South Korean navy ship firing toward an unidentified vessel to the north.

North Korea in recent weeks has said it was bolstering its defenses in response to joint South Korean-U.S. military drills that were held this month.

UPDATE FROM SKY NEWS 2:30PM EST: A South Korean naval vessel has sunk in waters near North Korea after an explosion ripped through the ship and more than 40 crew are still missing. The ship – reported to have 104 crew on board – sank off the coast of South Korean-controlled Baengnyeong Island close to the disputed maritime border with North Korea.

According to an official at the Joint Chiefs of Staff, the explosion occurred about 10.45 pm local time, but the exact cause was not immediately clear.

South Korea’s Yonhap news agency reported an explosion near the stern of the 1,200-ton ship and an early report suspected a torpedo attack from a North Korean ship.

Another South Korean ship reportedly fired on an unidentified target in the direction of North Korea, but South Korea’s government played down fears that it was an attack.

The Joint Chiefs official could not confirm the shooting but said the military was strengthening its vigilance in the territorially tense area.

The incident comes amid heightened tension between the two Koreas, which remain in a state of war because their three-year conflict ended in a truce, not a peace treaty, in 1953.

President Lee Myung-bak convened an emergency meeting of security-related ministers, Yonhap said, citing presidential spokeswoman Kim Eun-hye.

Six naval ships and two coast guard vessels were rushed to the waters to rescue the crew, with 58 being saved so far.

The disputed border in the Yellow Sea was the scene of deadly naval clashes in 1999 and 2002.

North Korea’s military had earlier accused the US and South Korea of trying to topple the Pyongyang regime and said it was ready to launch a nuclear deterrence.

The military General Staff cited a South Korean newspaper report as evidence of “desperate moves of the US imperialists and the South Korean puppet warmongers” for regime change.

A General Staff spokesman warned the official Korean Central News Agency that there would be a retaliation for any attack.

“Those who seek to bring down the system in the DPRK (North Korea)… will fall victim to the unprecedented nuclear strikes of the invincible army,” he said.

(Source:  http://www.washingtonpost.com/)