Indian police have arrested five senior oil company executives in a widening investigation into the alleged theft of classified government documents.

The five new suspects were being interrogated Saturday along with seven others charged earlier with trespassing, forgery and theft of documents from India's oil ministry.

Delhi Police Commissioner Bhim Sain Bassi also said officers had raided a company's offices in the suburb of Noida after arresting one of its consultants.

He said more raids were possible as "our aim is to reach the bottom of the whole thing."

The first arrests were made by authorities acting on a tip about the alleged leaking of ministry documents.