TESERO, Italy (AP) _ About 3,000 mourners gathered Thursday to honor and bury 51 unidentified people killed when an earthen dam collapsed and inundated the alpine village of Stava under tons of water, mud and debris.

More than 200 people were killed last Friday when the dam in northeastern Italy broke and wiped out Stava's 20 homes and three hotels.

The wooden coffins of the unidentified victims, who were mangled or decomposed beyond recognition, were carried one by one through the silent crowd on the shoulders of soldiers.

Many people cried. Others threw flowers as the coffins were placed in a huge common grave behind the Church of St. Leonard in this town directly below Stava.

The burial was preceded by a funeral service in a field next to St. Mary in Pain Church in Cavalase, near Stava, where the flower-covered coffins lay on military vehicles.

Monsignor Severino Visintainer, vicar-general of the Trento diocese, said In his homily: ''We must say a word for faith and hope, of which we, more than anyone, feel the weight.''

He said he hoped ''there will be a growing consciousness of the acute responsibility we have towards those around us.''

Although many victims came from elsewhere in Italy, they were buried in Tesero because ''the tragedy occurred up there, and it seems more humane that they should be reunited there,'' said Dr. Bergamo Andreis of the provincial health office in Trento.

Nine more decomposed bodies were pulled from the mud Thursday, bringing the number of confirmed dead to 213, said Elveno Pastorelli of the Civil Protection Ministry.

Ministry officials earlier said 37 bodies remained unidentified, but later revised the figure to 51 without explanation. There were still widely varying reports of the number of people missing, ranging from 53 to 161.

In Rome, Premier Bettino Craxi established a special seven-member government commission of officials and experts to investigate the disaster.

Local authorities Thursday arrested Mario Garavana and Alessandro Bassanelli. Both men are officials of the Prialpi Mining Co., which used the two reservoirs the dam supported to clean flourit, which is used in making glass.

Brothers Giulio and Aldo Rota, who owned the mining company and the dam, and Matteo Romasi, a forestry inspector for the Stava area, were arrested earlier. All five were charged with multiple manslaughter and causing a disaster, which carries a maximum penalty of 12 years in prison.

Investigators have said they were trying to verify reports that the mining company had been enlarging the reservoirs illegally.

Giulio Rota denied the charge. He said the work expanding the reservoirs was legal and reports on its progress had been sent to authorities every three months.

Prosecutor Francesco Simeoni said more arrests were likely. His office in Trento has sent dozens of judicial notices to people, informing them that they are under investigation and face possible prosecution in connection with the disaster.

Meanwhile, civil defense officials held marathon meetings Thursday, mapping strategy for the protection of Tesero residents and their property from a possible mud slide.

It rained briefly overnight and the weather bureau predicted more showers for Friday, sparking fears the rain could touch off a massive slide down the valley from Stava to Tesero.