Prosecutor Yury Basov confirmed that the probe relates to a Russian association of trade unions' inquiry into the legitimacy of key company positions being held by foreign managers, as well as the possible abuse of Russian employees' rights.
"Although there is a lot of material to be examined, I believe the check will be completed by the end of this month," Basov said.
Basov earlier confirmed reports that representatives of TNK-BP CEO Robert Dudley had brought the requested documents to the prosecutor's office earlier on Monday. Dudley himself failed to show up for an interview, which Basov said was his right.
Business daily Kommersant said on Monday that Dudley was supposed to provide prosecutors with personnel vacation schedules for the past two years, payroll journals from January-May 2008, TNK-BP Management personnel files, and other documents.
BP, which holds 50% in the joint venture, recalled 148 employees in Russia over alleged visa problems in March. The move came amid mounting pressure on the company after a police raid on its Moscow office and the joint venture, and the arrest of an employee on industrial espionage charges.
Basov said TNK-BP Vice President Clark Cridland, Human Resources staffers, and other employees had visited the prosecutor's office bringing some of the requested documents. More documents will have to be provided later, the prosecutor said.
Basov refused to specify what sanctions TNK-BP, Russia's third largest oil producer, could face if the violations are shown to have taken place.
On Tuesday, Dudley is to be questioned at the Interior Ministry's investigation department, Kommersant said. The paper cited a source close to TNK-BP shareholders as saying the questioning would be over back tax claims against the company for 2001-2003. Dudley took the position in 2003, when the joint venture was created.
Questioning will take place amid a dispute between the TNK-BP Russian and British shareholders, which is believed to relate to the firm's ownership and development strategy, in particular its international expansion.
Analysts have suggested the dispute could result in the company being bought up by state-controlled Gazprom or Rosneft as part of the Kremlin's campaign to toughen its grip on the oil and gas sector.
