Yanukovich of the pro-Russian Regions party had accused the government of thoroughly mismanaging the economy.
"There must be early elections to parliament and for president," he said.
Irina Akimova, another member of the party, said: "The Ukrainian economy is heading for disaster".
But Tymoshenko dismissed the charges, insisting Ukraine's economy would grow by 0.4 per cent, despite International Monetary Fund (IMF) predictions of a contraction of 5 per cent in 2009.
"The government did not agree with such a forecast," she said.
"It is simply too easy to become reconciled to a fall. I believe Ukraine is strong, with resources and reserves and if the proper actions are taken at this difficult time, we can achieve this indicator as planned," she said.
The global economic crisis has hit Ukraine's economy hard, with a sharp drop in demand for two of its primary exports - steel and chemical products.
Its currency, the hrynia, lost nearly half of its value against the dollar in the last six months of 2008.
The country is due to hold presidental elections in late 2009 or early 2010.