Ukrainian President Viktor Yanukovych on Thursday rejected calls to intervene over the arrest of opposition leader Yulia Tymoshenko, saying he could not interfere in the work of the courts.

"I cannot and will not interfere in the work of the courts. If I did, the problems would be even greater," Yanukovych said in a statement released by his office, his first comments on the case since Tymoshenko was arrested last week.