Ukraine`s interior minister, a key figure in an ongoing political crisis, who was hospitalized Wednesday after a heart attack, remains in a serious condition, the ministry said Thursday, according to RIA Novosti.

      Vasyl Tsushko`s lawyer, Tatyana Montyan, told local TV on Wednesday night that she believed the minister had been poisoned.

      The president accused Tsushko of committing a "grave crime" during turmoil last week following the dismissal of the country`s top prosecutor, and the new acting prosecutor said the interior minister faces investigations of abuse of power.

      Last Thursday, Western-leaning President Viktor Yushchenko dismissed his long-time opponent Prosecutor General Svyatoslav Piskun, but the interior minister defied the president`s order, sending in riot police to defend the prosecutor who remained in his office while protestors gathered outside.

      President Yushchenko said on Wednesday that Tsushko must be called to account for his actions and the chaos that ensued.

      "I am sure that this is a serious crime," Yushchenko said. "This was an act for which the interior minister should be personally called to account."