A navy frigate that ran aground in the waters off China's Nansha Islands was refloated with the help of the navy's rescue force on Sunday, relieving concerns amid rising tensions in the South China Sea.

The forward hull of the ship was slightly damaged, but all crew members were safe and the ship will sail back to port, according to a news release on the Ministry of National Defense's website.

"It has not caused any contamination in the waters," the statement said.

The frigate has been in service for 19 years and is still in its "prime of life", said Li Jie, a navy analyst in Beijing, refuting speculation that the frigate's stranding was planned.

The Philippines has dispatched one navy and one coast guard ship to the area to monitor the Chinese operations, according to AFP.

Overlapping claims to the islands in the South China Sea have caused tensions in the area. The Philippines, Malaysia, Vietnam, Indonesia and Brunei all claim sovereignty over some islands in the South China Sea.

Chinese and Philippine officials are seeking a resolution to the standoff over Huangyan Island, which has lasted for more than three months, according to The Associated Press.

The Philippines on Sunday said it would not lodge a diplomatic protest after China extricated the naval frigate, which had been stranded for four days, AFP reported.

"We don't believe that there were ill-intentions that accompanied the presence of that ship in our exclusive economic zone," said Foreign Secretary of the Philippines Albert del Rosario.

Philippine Defense Secretary Voltaire Gazmin said on Sunday the Chinese frigate apparently made a navigational mistake that caused it to run aground.

He said there appeared to be no signs that it was on a mission to intrude in a Philippine claimed area, noting the absence of structures on the shoal.

Xu Liping, an expert on Southeast Asian studies at the Chinese Academy of Social Sciences, said China's military activities in this area are normal for the country to safeguard its territory.

"Running aground is nothing new for a country's navy. The timely release of the information also shows that China's activities in the South China Sea are transparent," Xu said.

Fishing operation

Thirty boats taking part in a fishing operation reached the Nansha Islands in the South China Sea on Sunday.

Their destination was the waters near the Nansha Islands' Yongshu Reef.

They set off on Thursday from South China's Hainan province, starting on what is to be a 20-day operation. Local authorities called the trip one of the largest in the Hainan fishery's history.

Every year, fishermen in Hainan organize a month-long fishing operation. This time, though, local fishing associations took the lead in arranging the event.

Ships patrolling the waters off Sansha city are preparing to deal with various situations that might arise during the fishery operation.

In late June, China established Sansha city to administer the three island groups of Nansha, Xisha and Zhongsha.

Contact the writer at chengguangjin@chinadaily.com.cn