Russia has more in common with Nigeria these days than just oil.

Following up on the politically charged jailing of oil tycoon Mikhail Khodorkovsky, a wave of scam e-mails in the style of Nigeria's notorious spammers have been popping up in inboxes from Moscow to Kentucky.

But instead of impassioned pleas by dead African dictators' aides to move millions of dollars overseas, the appeals appear to come from the inner circle of the man who was once Russia's richest.

"Dear friend, I got your reliable contact from my husband's business diary ..." begins one letter from "Leila Khodorkovsky," claiming to be the billionaire's wife — whose actual name is Inna.

The letter requests assistance investing $45 million of the tycoon's money and promises compensation.

Another is signed by "Larissa Sosnitskaya," who describes herself as a personal treasurer to Khodorkovsky, seeking a beneficiary for a similar sum that she intends to use "to relocate to the American continent and never to be connected to any of Mikhail Khodorkovsky conglomerates."

While their details — and often grammar — are muddled, the Khodorkovsky-themed spam highlights the notoriety of his case and his eight-year sentence on tax and fraud charges, which critics called Kremlin revenge for his sponsoring of opposition parties.

Worth some $15 billion before his arrest at gunpoint on a Siberian airfield in 2003 — and currently an inmate of a bleak prison colony on Russia's border with China — Khodorkovsky was an obvious choice for the authors of the Nigerian-style spam, experts say.

"This is a well-developed business — they choose what is up-to-date," said Yevgeny Altovsky, who coordinates a UNESCO-backed anti-spamming program in Moscow.

"The main thing is it has to involve some kind of rich person," he said. "If a major court case against Bill Gates were to start tomorrow, I'm sure he would appear in these messages."

Yukos spokeswoman Claire Davidson declined to comment on why spammers might have selected Khodorkovsky and the company he founded as subject matter.

"They aren't being issued from within the company," she said, referring to one letter in circulation allegedly signed by Bruce Misamore, Yukos' former chief financial officer.

While versions of the letter from Khodorkovsky's managers have been sent in Russian, Altovsky said Russian Internet users are wise to such scams and were unlikely to be fooled.

Indeed, the Russian market for spam differs widely from the more aggressive U.S. fare of online casinos, porn sites and erectile dysfunction drugs, and is used primarily by small and medium businesses as a means to advertise. Nonetheless, the Russian practice causes some $30 million a year in damages from traffic costs, Altovsky said.

Nigeria — globally recognized as a base for criminals exploiting the reach of the Internet — said in October that it is considering making spamming a criminal offense that could land senders of unsolicited e-mails in jail for three years.

Africa's most populous country is known for its "advance fee" scammers — criminals scouting for victims by sending millions of unsolicited e-mails with false proposals around the world.

Among the most common are e-mails proposing to share portions of dead African dictators' ill-gotten estates in exchange for an advance payment to help move the money overseas. The scammers keep the "fees" while victims receive nothing.

Khodorkovsky's case was accompanied by a sweeping back tax investigation at his Yukos oil company that eventually saw its main production unit sold in a disputed auction and eventually ending up in state hands.

Yukos managers have since fled Russia as their colleagues were jailed and arrested in the continuing probe.