Prime Minister Evgenii Primakov and influential billionaire tycoon Boris Berezovskii - two old and uncompromising political opponents - recently discovered they have something in common: back problems.

Primakov recently spent two days on sick leave, suffering from an exacerbation of lumbar spine osteochondrosis and subsequent radiculitis. Berezovskii checked into the Central Clinical Hospital (CCH) on April 18 - immediately following his arrival in Moscow from Paris - due to post spine trauma complications resulting in reduced movement and acute backaches, similar to the prime minister's.

Berezovskii's hospitalization prevented him from appearing at the prosecutor general's office for questioning the following day.

Similarities between the two politicians' ailments, however, end at the source of their physical pain.

Few doubt the legitimacy of Primakov's back troubles after seeing the prime minister in front of television cameras. His awkward movements in the Federation Council last week and at a cabinet session on April 7 made it obvious the prime minister was in pain.

On the contrary, Boris Berezovskii's swift and easy steps down the ladder of his jet to his limousine at Sheremetevo-1 suggested he was bursting with energy. He truly seemed capable of running a few hundred meters.

Primakov has been trying to avoid physicians and remain at work since his ailment began. Neither doctors nor relatives could persuade him to check into the CCH to have his osteochondrosis treated comprehensively - as is usually the case - over the course of 7 to 10 days.

According to members of Primakov's entourage, the prime minister insisted on a riskier short-term treatment, involving tough and painful massaging and the use of strong medicine. This method enables a patient to return to work the very next day, but increases the risk of complications.

Primakov ultimately agreed to a compromise of two days of treatment performed at home. On April 10, the prime minister returned to the White House to make a televised address to the nation in which he defended his government's record and responded to the president's remarks that he was not indispensable.

The version given by Primakov's entourage is the prime minister remains a healthy man despite his age. They say he simply has no expertise in falling sick in public, and has treated his ailment as an annoying obstacle, rather than a convenient excuse for relaxing in hospital.

A far more likely reason for Primakov's behavior, however, is his conflict with the presidential administration. The confrontation looms large and the prime minister's hold on power remains shaky. He knows it is not a good time for a vacation.

Primakov now seldom leaves government quarters. Some events he was scheduled to attend have been cancelled, including a proposed meeting with World Bank Director James Wolfenson two weeks ago.

The Kremlin did not hesitate to react. The prime minister has recently become a target for the president's stinging remarks such as: "I am in a good shape, I have no residual effects nor complications, and I am ready for a fight together with you all."

Unlike Primakov, Berezovskii's weakness is not his health. On the contrary, his illness has provided Berezovskii with temporary cover in his cat-and-mouse game with prosecutors.

After the prosecutor general's office issued an arrest warrant for Berezovskii, one version of events has it, upon request of Russian authorities, Interpol followed standard procedure: putting pressure to freeze his private accounts in foreign banks and halting cash flows to his family members residing abroad. As the family's cash flow became critical, Russian law enforcement authorities kindly offered to come to terms with Berezovskii. In return, his family was guaranteed a restoration of its money supply.

According to a second version, Berezovskii's financial empire was crumbling. The tycoon's departure from Russia significantly reduced his influence over the once obedient Sibneft, Aeroflot and LogoVAZ companies and ORT television. Berezovskii had a choice: either return to Russia immediately and act resolutely to regain control, or surrender his empire and fortune in order to remain abroad.

Berezovskii's telephone negotiations with the presidential administration's key-figures, Yeltsin's daughter Tatiana Diachenko and one-time chief-of-staff Valentin Yumashev, provided guarantees for his immunity if he chose to return to Russia. Still, as long as Yuri Skuratov remains general prosecutor, tycoon's arrest remains a possibility. Berezovskii's idea had been to postpone being questioned until after Skuratov's dismissal, widely expected on April 21.

Version three has it that Berezovskii's business situation made it impossible to put off a return to Russia. Hence the rationale for falling sick upon arrival.

Regardless of which account one believes, Berezovskii's illness is an obvious farce. Primakov, on the other hand, does not want to be dismissed for health reasons. Meanwhile, observers are waiting to see how the illnesses of both will play out on the political scene.