BEIJING (AP) — A chemical leak in China's northeast killed at least three people, prompting alarmed officials in neighboring Russia to order continuous monitoring of air and water quality, news agencies reported Friday.

Few details were available about the leak Thursday in Qiqihaer city of Heilongjiang province. An investigation was under way, China's Xinhua News Agency reported.

Labs on the China-Russia border were regularly testing air and water quality after Russian Prime Minister Vladimir Putin ordered "permanent monitoring" of the situation, the Interfax news agency said.

Qiqihaer is located only 250 miles from the Russian border and lies along a major tributary of the Songhua River, which flows into Russia.

A 2005 chemical spill in the Songhua strained China-Russia relations after poisoned waters flowed across the border. The spill included potentially cancer-causing chemicals and forced the northeastern Chinese city of Harbin to sever water supplies to 3.8 million people for five days.

Russia's Environment Minister said Friday that China failed to provide information about the latest accident and has sent an official note to complain and request information, Russian news agencies reported.

"Unfortunately, we have no official information from the Chinese side, which violates an agreement signed by the Environment Minister and China's Committee on Ecology. We have sent the appropriate note and hope for a response in the nearest future," state-run RIA-Novosti quoted Yuri Trutnev as saying.

The Communist Party propaganda office in Qiqihaer city had no immediate comment on the leak. Phones rang unanswered at the local police department.