BEIJING: China has urged the United States to end military surveillance operations in its coastal waters, but a US official said Friday that Washington's policies were unchanged.

"The constant US air and sea surveillance and survey operations in China's exclusive economic zone is the root cause of problems between the navies and air forces of China and the US," China's defence ministry said in a statement.

"The way to resolve China-US maritime incidents is for the US to change its surveillance and survey operations policies against China, and decrease and eventually stop such operations," the statement said.

The request came during two days of talks this week in Beijing between the two militaries on maritime issues, said the statement, posted on the ministry website early Friday.

The meetings come as part of efforts by both sides to overcome recent tensions sparked by confrontations between Chinese and US vessels in the South China Sea in March this year.

The United States agreed to continue to explore and discuss ways to improve maritime safety between the two nations, the statement said.

An official at the US embassy in Beijing told AFP that US policy on the issue had not changed.

"The United States exercises its freedom of navigation of the seas under international law, while putting emphasis on avoiding any unwanted incidents," embassy spokeswoman Susan Stevenson said.

"This policy has not changed."

China has insisted that US naval vessels entering its exclusive maritime economic zone, which stretches 200 nautical miles from its coast, must abide by Chinese law.

The United States has meanwhile insisted that it is free to navigate in waters outside China's territorial waters, which end 12 nautical miles from the coast.

In two separate incidents in March, Chinese fishing boats confronted US naval surveillance vessels and attempted to interfere with their operations. Beijing accused the US ships of engaging in espionage activities.