The Corruption Eradication Commission (KPK) will investigate allegations that six Russian-made jets purchased by the Defense Ministry were unduly marked up, Defense Minister Purnomo Yusgiantoro announced on Tuesday.

"Please look into the purchase of the Sukhoi planes," Purnomo said after a meeting of the Committee for Defense Industry Policies (KKIP) in Jakarta.

The purchase of six Sukhoi fighter jets arose suspicion after Tubagus Hasanuddin, deputy chairman of House of Representatives Commission I overseeing defense and foreign affairs, claimed that the purchase may have been marked up by $50 million.

A Sukhoi jet cost $55 million in Indonesia's 2007 purchase, the lawmaker said. But the latest purchase of six Sukhoi jets cost the government $470 million, or $78 million per plane. Russia's state-run military exporter, JSC Rosoboronexport, lists the price at $70 million per plane.

Tubagus suspected that the ministry had used a middleman to make the purchase, a claim Purnomo denied on Tuesday. "There are only two parties in the contract, namely JSC Rosoboronexport and the Defense Ministry," he said.

All military purchases are highly-regulated, passing through two supervisory committees, to reduce the likelihood of price irregularities, the Defense Minister said. But if the KPK believes there have been irregularities in the purchase, the ministry will allow the antigraft organization to investigate, he added.

A price increase between the 2007 purchase and the most recent one is normal, Purnomo said. "The span of time between the two contracts is 5 years, so there has to be a price change," he said.

The listed price also included more than just the planes, Purnomo said. The ministry also bought spare parts and technical coaching from the Russian exporter. The jets are set for delivery in July. They will be housed at Makassar's Hasanuddin Air Force Base, where ten other Sukhoi jets are currently in stationed.