North Korea fired another short-range missile from its east coast on Sunday, following the launch of three missiles Saturday, South Korea’s Yonhap news agency reported.

"North Korea fired a short-range missile as it did yesterday into its east sea in the afternoon,” Yonhap said.

The South Korean Defense Ministry official confirmed the report, but gave no details.

U.N. Secretary General Ban Ki-moon, a South Korean, called on the Communist North to refrain from further launches and return to stalled nuclear talks with world powers. Speaking to Russian state news agency RIA Novosti during a visit to Moscow, he called Saturday's launch a "provocative action." Ban also called on Russia -- a member of the stalled six-party talks on North Korea's nuclear program -- to help bring Pyongyang back to the negotiating table, the BBC reported. Tension on the Korean peninsula has subsided in the past month, following several weeks of agitation after the U.N. Security Council imposed tougher sanctions against Pyongyang following its third nuclear test in February.

Meanwhile, unidentified North Koreans are holding a Chinese fishing boat and its 16 crew members and have demanded a ransom, Chinese media and the boat owner say.

Owner Yu Xuejun said on a microblog that the boat was floating in Chinese waters on May 5 when it was boarded and detained by gun-wielding North Koreans, the Associated Press reported. He wrote on Tencent Weibo late Saturday that the "North Korean side" had demanded 600,000 yuan ($100,000).

Yu said he had turned to the Internet to issue an appeal for help and because he wanted the Foreign Ministry to pay attention.

Calls to the maritime police and foreign and public security ministries rang unanswered Sunday, the AP said.

The Southern Metropolis Daily Yu received a call from North Korea saying his boat had entered North Korean waters. It quoted an unnamed official from Liaoning maritime police as confirming the case had been reported to them on May 6 and a team was handling it.

Yu said the North Korean side had asked for the ransom to be paid by noon Sunday to a company in Dandong, a city in northeastern China on the North Korean border, or they would confiscate the boat and repatriate the crew. Yu's last contact with them was Saturday. The newspaper didn't mention whether he had paid any money.