KIEV, August 10 - RAPSI. Convicted Ukrainian Prime Minister Yulia Tymoshenko has refused to participate in a U.S. court hearing by video conference, the Ukrainian State Penitentiary Service reported on Friday.

According to the service, the former prime minister said she is undergoing rehabilitation at a hospital, and German and Ukrainian doctors have asked her to avoid unnecessary stress.

Universal Trading & Investment Co. Inc. (UTICo), which has been unsuccessfully attempting to recover $18.3 million from United Energy Systems, which Tymoshenko headed in the 1990's, submitted a lawsuit to the U.S. District Court for the Southern District of New York in November 2011. Since the defendant did not react on the lawsuit's submission, UTICo submitted an appeal in April to consider the lawsuit in the second party's absence.

The plaintiff agreed to speak with Tymoshenko by video conference or telephone.

The conversation was scheduled to take place everyday except for Sunday.

The court hearing into the Universal Trading & Investment Co. Inc vs. Yulia Tymoshenko case was set for September 5.

In October 2011, Tymoshenko was sentenced to seven years in prison for abuse of power after signing a gas contract with Russia in 2009. She is serving her sentence in a Kharkiv women's prison. She has been receiving treatment at a Kharkiv hospital since May 2012. She was diagnosed with a spinal disc herniation.

In late March, a second case against Tymoshenko was submitted to the Kharkiv Kievsky District Court. The case deals with her activity at United Energy Systems. She is suspected of financial machinations.