UPDATE 2-Brazil senators to probe petrochemical Braskem's sinking ground havoc

(Adds Braskem's comment in paragraph 8)

BRASILIA/SAO PAULO, Dec 13 (Reuters) - Brazil's Congress committed on Wednesday to a federal investigation into petrochemical company Braskem over the sinking soil in the city of Maceio, which has forced about 60,000 people to be moved since 2018.

The launch of an official investigation in Brazil's Congress follows a Sunday breach of one of Braskem's more than thirty salt mines under Maceio, a coastal city with nearly 1 million people in Brazil's northeast region.

A video released by Maceio's city hall shows a flow of brown-colored water suddenly emerging to the surface of a lake located above the mine.

Maceio's Civil Defence, which in November warned of an "imminent risk of collapse", said on Monday it still didn't know if Sunday's incident was either a partial break or a total collapse. People had already been evacuated from the area, it said.

Braskem's mines began extracting rock salt in the 1970s in Maceio, but operations were halted from 2019 after authorities said it contributed to five neighborhoods sinking.

The company then spent about 9.2 billion reais ($1.85 billion) on socio-environmental agreements, while more than 5 billion reais are provisioned.

The latest events could further increase costs related to Maceio's sinking ground, with public authorities already filing new repair pledges, sending the company's shares down 12.2% this month alone up to Monday.

Braskem said in a satement it will make itself "available, as always, to respond transparently about activities in Maceio."

The committee installed on Wednesday by Brazil's senators have the same inquiry powers as law authorities, but may only start working in 2024 as Brazil's Congress recess nears.

These committees, known as CPIs, usually have a lot of public exposure, although they don't always end with lawmakers, who run the probe themselves, asking for indictments.

It remains unclear if the inquiry could impact Braskem's stake sale process by Novonor, which controls the firm together with state-controlled oil firm Petrobras. Abu Dhabi oil company ADNOC presented a non-binding offer in early November. ($1 = 4.9665 reais) (Reporting by Maria Carolina Marcello and Andre Romani, Additional reporting by Alberto Alerigi Jr., Editing by Isabel Woodford and Aurora Ellis)