A North Korean boat hijacked three boats with 29 Chinese fishermen on board and demanded 1.2 million yuan ($190,000) for their release, Chinese media reported Thursday. It was unclear if a territorial dispute or piracy was behind the incident involving boats from the two communist-led nations. China is the North's biggest diplomatic ally and source of economic assistance. The fishing boats were hijacked in a Chinese section of the Yellow Sea on May 8 and moved to North Korean waters, the Beijing News reported. Border police in northeastern China's coastal Liaoning province told the state newspaper they were in contact with the North Korean captors but declined to comment further. Chinese Foreign Ministry spokesman Hong Lei said Thursday that Beijing is in close contact with North Korea about the situation and hopes it can be resolved as soon as possible. "We urged the North Korean side to guarantee the legal rights of the Chinese fishermen," Hong said at a regular news conference. He refused to elaborate or clarify whether the payment allegedly being demanded was considered a ransom. South Korea's coast guard says it has seized hundreds of Chinese ships over the years for illegal fishing in the Yellow Sea, which is rich in blue crabs, anchovies and croaker. The ships are usually released after a fine is paid, though violence occasionally occurs. In 2008, one South Korean coast guard officer was killed and six others injured in a clash with Chinese fishermen in South Korean waters.