HANOI (Reuters) Mon Dec 8, 2008 - Hundreds of Vietnamese police and riot police sealed off streets leading to a government building on Monday as eight Catholics went on trial over their attempt to claim a plot of disputed land in the capital.

More than 1,000 Vietnamese Catholics turned up at the People's Committee offices in a Hanoi district to protest against the trial, a rare expression of dissent against the southeast Asian country's ruling Communist Party.

In a peaceful demonstration, the Catholics sang hymns and held up banners demanding justice for the eight, whose court appearance is the latest twist in a dispute that has been rumbling on for months.

The piece of land in question is owned by a garment company but the protesters argue it is church land.

In August, state television showed pictures of people using hoes and hammers to break what it said was a section of the brick wall surrounding the plot, leading to police claims of "causing public disorder" and "intentional destruction of property."

"They're trying these eight people to send a message to the rest," one of the protesters told Reuters, asking not to be named for fear of recrimination.

Religion remains under state supervision in the mostly Buddhist country, although Vietnam has the second largest Catholic community in Southeast Asia after the Philippines, with about 6 million among the 86.5 million population.

The Hanoi government is working toward establishing formal diplomatic relations with the Vatican, and Prime Minister Nguyen Tan Dung visited the Pope there a year ago.

(Reporting by John Ruwitch; Writing by Ed Cropley; Editing by Alan Raybould, http://www.reuters.com/article/worldNews/idUSTRE4B70Q720081208)