RIO DE JANEIRO (Reuters) - Brazilian federal prosecutors are seeking the arrest of a Vale SA senior executive, authorities said on Friday, following the collapse of a dam holding mining byproducts that is believed to have killed over 300 people.

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This is the first time that prosecutors are seeking to detain a senior-level executive, although several mid-level employees were arrested after the disaster in the town of Brumadinho. Eight employees are still being held.

The executive, Director of Ferrous Metals Peter Poppinga, has not been arrested after a judge declined to issue a warrant. But prosecutors told Reuters they are still seeking his arrest in an appeal of the judge’s decision.

“Poppinga represented a risk to the public order and his freedom could hurt the enforcement of criminal law,” said prosecutor Gustavo Oliveira in the arrest request originally filed on Feb. 11.

The prosecutor said in the arrest request that Vale and particularly its Ferrous division were ultimately responsible for the Brumadinho disaster. The causes of the dam collapse are still being investigated.

A federal judge disagreed, saying in his decision that the fact that Poppinga continued as an executive director at Vale did not pose a risk to the public or economic order.

Vale said in a statement that it considered the judge’s decision “absolutely right,” adding that it is certain that none of its executives acted with intention to cause any accident.

The Vale executive is already a defendant in criminal lawsuits resulting from a previous dam burst, where 19 people died in 2015 in the town of Mariana, located in the same state as Brumadinho.

Poppinga was a board member of Samarco, the joint venture between Vale and BHP Billiton that managed the dam that burst in Mariana, in Brazil’s largest ever environmental disaster.

The death toll from the burst dam has risen to 169 people, with 141 people still missing and probably dead.