HANOI, June 19 Several dozen Vietnamese protested in front of the Chinese embassy and marched through Hanoi for the third Sunday running after Beijing sent one of its biggest maritime patrol ships into the disputed waters of the South China Sea.
The demonstration comes amid the biggest flare-up in tension in years over competing sovereignty claims in the sea, home to key shipping lanes and fisheries and potentially large deposits of oil and gas.
Neither Vietnam nor China has shown much willingness in the past month of strained relations to back down, with both staging military exercises and accusing the other of sovereignty violations.
Last week, China sent the Haixun 31, which official media said was one of two maritime patrol ships the same size, to monitor shipping, carry out surveying, inspect oil wells and "protect maritime security" in the sea en route to Singapore.[ID: nL3E7HG0I5]
About 40 protesters chanted slogans including "Oppose China! Down with China!" under a statue of the Russian Communist revolutionary Lenin in a park across from the Chinese Embassy for about a half hour. Police then forced them to leave, announcing that their protest had been heard and that staying could "complicate" diplomacy.
"We protest out of frustration and to show that we should not be soft and weak when it comes to China," said Le Mai Dau, a retired officer of Ministry of Transportation.
With police blocking traffic, the protesters marched to the centre of town waving banners and flags, singing patriotic songs and chanting. The crowd swelled to about 100 along the way.
"We have defended our country numerous times and for many years -- against the Mongols, against the Qing Dynasty, against the French, against the Americans, against the Chinese. If anyone at all tries to invade us we will all stand up to defend our motherland," said protester Dang Bich Phuong.
Political protests are rare in Vietnam and the relationship with China is considered the most sensitive. But diplomats and political analysts say Vietnamese policymakers have become increasingly frustrated by China's growing assertiveness in the South China Sea.
The latest bout of tensions escalated after the Vietnamese government made public an incident in late May in which it said a Chinese vessel intentionally cut submerged cables in use by a Vietnamese seismic survey ship within Vietnam's 200 nautical mile special maritime economic zone.
"That crossed a line for them," said a diplomat who declined to be identified.
Incidents of harassment between claimants to the South China Sea are not uncommon. Brunei, Malaysia, the Philippines and Taiwan also hae claims.
On Friday in Washington, Vietnamese and U.S. officials committed to strengthening their relationship and discussed maritime security and the South China Sea during the fourth political, security and defence dialogue.
"We do not tolerate a kind of behaviour from China of saying one thing and doing the opposite," said Le Dung, a 42-year-old electrical engineer who took part in Sunday's protest in Hanoi.
"We want the Vietnamese government to invite international observers to come to the East Sea (South China Sea) so the whole world can see that Vietnam is acting within the law and in accordance to international law, so that China must also abide to the law and international law." (Additional reporting by Reuters TV; Editing by Nick Macfie)