The chairman of the commission, Volodymyr Syvkovych, has called on Austrian doctors to immediately provide to the commission and the Ukrainian Prosecutor-General's Office all materials related to the doctors' finding that Yushchenko was poisoned by a large quantity of dioxin.
The determination of poisoning has prompted Ukrainian prosecutors to reopen a criminal investigation of the case.
The United States has meanwhile rejected allegations it has been interfering in Ukraine's internal affairs by funding Yushchenko's campaign.
The charges of U.S. meddling were made yesterday by Prime Minister Viktor Yanukovych, Yushchenko's rival in the 26 December rerun of the presidential runoff.
U.S. State Department spokesman Richard Boucher said the United States does not have favored candidate in the Ukrainian election.
"We will make our position clear once again -- that we did not have a favored candidate in the campaign. Our interest is in seeing democracy prevail," Boucher said.
Boucher said Washington seeks to assist independent media and democracy-building organizations, and that U.S.-backed programs have been open to all parties on an equal basis.
Yushchenko's supporters have said Yanukovych is supported by Russia.
(ITAR-TASS/Interfax/AP/AFP/Reuters)For more RFE/RL coverage and analysis of the political crisis in Ukraine, click here.