(Adds details of investigation, background)
LIMA, Jan 12 (Reuters) - Peruvian prosecutors raided the offices of local construction conglomerate Grana y Montero , Brazilian builders OAS and Andrade Gutierrez and other companies on Friday, the attorney general's office said on Twitter.
Grana y Montero said it was cooperating with the "construction club" investigation led by a team of prosecutors tasked with fighting corruption.
OAS did not immediately respond to requests for comment.
Andrade, which has signed a plea deal in Brazil over kickbacks in the country's massive "Car Wash" graft scandal, declined comment.
The attorney general's office has not provided details on the wrongdoing it suspected the companies had been involved in.
Prosecutors in Peru have been probing construction companies to determine if they colluded to secure contracts or took part in some $30 million in bribes that Brazilian builder Odebrecht has acknowledged paying to local officials.
As part of the operation on Friday, authorities targeted 42 properties and arrested a former adviser to the Transportation Ministry, one of six people it expected to detain, the attorney general's office said.
Peru is set to award some $2.2 billion in contracts this year to rebuild infrastructure damaged by flooding.
Last year, the government barred companies that have acknowledged or been convicted of corruption from taking part in new contracts, and restricted Odebrecht's financial transfers.
Grana, Peru's biggest builder, has repeatedly denied wrongdoing. Last month, the company's former chairman and three other construction executives were placed in pretrial detention over bribery allegations that they deny.
"Grana y Montero reaffirms that the company is opposed to any anti-competitive practice, and welcomes the investigation that is under way," Grana said in a statement.
Grana's shares in Lima had risen by 2.5 percent before falling back to a 2 percent gain after the attorney general office's announcement.
(Reporting By Mitra Taj; Editing by Rosalba O'Brien and Peter Cooney)