Frustrated Russian investigators said Friday they may press charges against the country's former defence minister after he refused to answer questions about his alleged role in a huge illegal property scheme.

The state's powerful Investigative Committee interrogated Anatoly Serdyukov for the second time in two weeks as part of a probe into a scam worth up to $230 million run by his subordinates.

Russia's first civilian defence minister was fired shortly after investigators seeking to question one of his assistants were met at the woman's front door by Serdyukov dressed in a bathrobe.

Serdyukov refused to answer questions at the first Investigative Committee hearing and on Friday appeared slow to address the security agency's concerns.

"After failing to receive an answer to a single question ... it is quite likely that Serdyukov's procedural status may change (from that of a witness)," said committee spokesman Vladimir Markin.

The Interfax news agency later reported that prosecutors were looking to charge Serdyukov for illegally authorising the construction of an eight-kilometre (five-mile) road to one of his relative's houses.

Interfax said Serdyukov told the investigation that he had no idea authorising such work was against the law.

Serdyukov's high-profile defence team sounded confident as journalists swarmed for a glimpse of the unusual sight of a former Kremlin insider being asked about his spending habits.

The former defence minister's lawyer Genrikh Padva said Serdyukov "gave as much evidence as he could."

"I do not think that he will be called in for questioning again for a long while -- maybe never," the celebrity defence attorney said told Russian media.

Television footage showed Serdyukov arriving at the committee's headquarters in a black Mercedes sedan with a bodyguard in the front seat.

Channel One state television said he spent nearly three hours being questioned.

The Kremlin has repeatedly stressed its commitment to fighting deep-rooted corruption that has ravaged post-Soviet Russia and weakened public trust in the authorities.

But few senior officials have faced criminal enquiries.

President Vladimir Putin fired Serdyukov over the corruption scandal in November and appointed in his place Sergei Shoigu -- Russia's longest serving cabinet member and one of its most popular politicians.

The new army boss faces the tricky task of continuing to push through personnel cutbacks aimed at streamlining the armed forces while updating equipment that for the most part was developed during Soviet times.

Serdyukov drew many enemies within the military industrial complex for deciding to steer new equipment purchases toward foreign products and cutting back some basic army services for the troops.

But he survived persistent dismissal rumours thanks in part to Putin's inability to find a reliable figure who could handle one of Russia's most thankless tasks -- decades-overdue army reforms.

Serdyukov's dismissal has freed the media to paint a picture of an armed forces command that is festering in corruption and oblivious to actual army demands.

He reportedly ignored several requests to appear for questioning after his ministry sold prime Moscow real estate to companies registered under the names of friends and their spouses.

Tens of millions of dollars also went missing from the military's huge maintenance and equipment upkeep fund under Serdyukov's watch.

Investigators said they were still at the early stages of the probe and needed to conduct further interviews and study evidence seized from the defence ministry.