GRENADES KILL 10 IN CAMBODIA : ATTACK DURING OPPOSITION POLITICAL RALLY MAY THREATEN DEMOCRACY.

Byline: Seth Mydans The New York Times

Cambodia's hard-won but increasingly tenuous democracy was shaken Sunday by a grenade attack that killed or injured scores of people at an opposition political rally in the center of the capital.

At least 10 people were killed and more than half of the 200 people at the rally in Phnom Penh were injured by the rapid series of explosions. It was the worst political violence since a democratic government was established here in 1993.

The apparent target of the attack, the opposition leader Sam Rainsy, escaped with only minor injuries, though he was covered with the blood of a bodyguard who he said leaped to protect him. He immediately blamed the attack on one of the country's two feuding co-prime ministers, Hun Sen, who has frequently threatened violence against his opponents.

A leading member of Hun Sen's Cambodian People's Party, Khie Kanharith, denied that the party was involved. ``The CPP has long experience with politics and does not commit acts of violence against innocent people,'' he said.

The country's fragile democracy has degenerated in recent months into a cold war between Hun Sen and the other co-prime minister, Prince Norodom Ranariddh, that occasionally has burst into exchanges of gunfire between soldiers loyal to each of the two government factions.

The confrontation has eroded the legacy of a $2 billion international effort sponsored by the United Nations in 1992 and 1993 to hold elections and establish a democratic government in Cambodia.

But political analysts said Sunday that they were stunned that large-scale political violence had erupted so far in advance of elections scheduled for November 1998.

``This does seem ominous,'' said David Chandler, a scholar of Cambodian history and politics. ``This much violence so soon is a surprise. It was a perilous, perilous thing to do.''

Western diplomats who continue to support Cambodia's corrupt and threadbare economy with large amounts of aid expressed fears that this international experiment in nurturing democracy could collapse.

``It is imperative that all in Cambodia do everything possible to avoid any future violence which could put at risk the significant progress Cambodia has made in recent years,'' the U.S. Embassy said after the killings in what seemed an almost pleading statement.