Days before Russia rolls out its largest annual economic forum, an ex-lawyer for Yukos who currently heads a nonprofit organization promoting transparency in business warned almost 1,000 foreign participants against going into the event with rose-colored glasses.

In a mass e-mail sent late last week, Pavel Ivlev, who fled Russia in 2005 and now leads the Committee for Russian Economic Freedom, reminded participants including Citigroup chief executive Vikram Pandit and ConocoPhillips head James Mulva that Russia is an "extremely dangerous" place to do business.

"As you listen to Russian officials and businessmen discuss potential gold mines in investing in Russia, be mindful that there are numerous land mines as well," reads the final line of his e-mail.

Several European leaders, including French President Nicolas Sarkozy, are expected to attend the international economic forum, which opens in St. Petersburg on June 17.

The three-day event is Russia's answer to the Davos forum and provides a platform for foreign corporate and political leaders to clinch billions of dollars worth of contracts and hobnob with the creme de la creme of Russia's political and business elite.

Ivlev, a former lawyer for oil firm Yukos, said his e-mail was a "call to action."

"I am not suggesting a boycott of the forum. Rather I am calling on the business community to stop being quiet and start speaking out about the lack of transparency and rule in law in Russia," he said by telephone from the United States.

Ivlev worked for an independent law firm in Moscow that represented Yukos, the former oil giant dissolved by the Kremlin and bankrupted in 2007.

Charges were brought against Ivlev in 2005 for theft, money laundering and helping Yukos in tax evasion schemes, two years after his client, the company's former CEO Mikhail Khodorkovsky, was arrested and jailed.