Ukrainian President Viktor Yushchenko says he believes a former ally and friend could have been involved in his nearly-fatal poisoning four years ago.

At a news conference Thursday, Mr. Yushchenko made allegations about the possible involvement of David Zhvania, a member of a pro-presidential parliamentary faction and godfather to one of his children. The president gave no evidence for his claim.

The charge marks a sharp departure from the president's previous refusal to identify who he thought was responsible.

It follows Zhavania's claims earlier this month that the president suffered only from "food poisoning." He accused Mr. Yushchenko's staff of inventing the poisoning story to gain the sympathy of the Ukrainian people.

Mr. Yuschenko fell gravely ill after attending a dinner with Zhvania during his presidential campaign in September 2004. Doctors said he had been poisoned with a highly toxic form of dioxin, most likely administered in a soup.

The poisoning left him severely disfigured, although his skin has improved dramatically since.

Earlier this month, the Russian Prosecutor-General's Office refused Ukraine's request to extradite another key figure in the poisoning investigation - former deputy chief of Ukraine's Security Service, Volodymyr Satsyuk.

The dinner where Mr. Yushchenko fell ill was at Satsyuk's home. Satsyuk, also a former member of Ukraine's parliament, has denied any involvement.

Some information for this report was provided by AP.