Alexander Tsygankov was arrested in Tripoli, the capital of Libya, on November 25. No official charges were pressed against him.
"There has obviously been some misunderstanding, and we have been told that it will be resolved in the next few days," Sergei Lavrov said.
A respected Russian business daily, Vedomosti, quoted a Libyan official early this month as saying that Tsygankov's arrest and the search of the company's offices were all connected to commercial espionage ahead of a December 9 tender for 12 prospective gas fields in Libya, comprising 41 blocks.
The Libyan official told the paper that his colleagues were investigating a confidential information leak regarding bids for the tender. A Foreign Ministry official said the main suspects were employees of Libya's national oil company.
Anatoly Martynov, the Russian Embassy counselor in Tripoli, said Tsygankov was "more of a witness in the case than a suspect."
At the December 9 tender, another Russian company, Gazprom [RTS: GAZP], was declared the hydrocarbon exploration and development tender winner for onshore Block 64 (Blocks 1, 2 and 3) located in the Libyan Ghadames Basin. Preliminary estimates say Block 64 contains 20 million metric tons of oil.
Libya holds Africa's second largest gas reserves, estimated at 1.47 trillion cubic meters. The December tender was the first open tender for the country's natural resources and involved 35 bidders, such as Gaz de France, Total, StatoilHydro, BP, Eni, ConocoPhillips, OMV, Wintershall, and Russian companies Gazprom, LUKoil Overseas and Novatek.