Thousands of people have rallied in the Ukrainian city of Kharkiv, calling on authorities to release former prime minister Yulia Tymoshenko from jail in the first major show of opposition in the east of the country.

The protest went ahead despite a local court order banning the demonstration and dozens of public transport vehicles blocking the rally's passage, an AFP journalist on the scene said on Friday.

Tymoshenko's supporters said they have been stopped from visiting her in prison, where she is already serving a seven-year sentence for abuse of office - a conviction the EU has called a case of selective justice.

Supporters of three opposition parties had to change their planned route because central squares and streets were blocked with trams and trolleybuses, causing a collapse in the transport system.

The demonstration still managed to attract a crowd of about 5,000 on the central square, according to police estimates.

The opposition called the rally to coincide with a court hearing in the tax evasion case against Tymoshenko in Kharkiv, which was postponed in her absence as she receives medical treatment in a local hospital.

Kharkiv authorities opposed the protest, and asked the court to ban it "in order to protect the interests of the Kharkiv residents," Mayor Gennadiy Kernes said.

The rally was led by Vitaly Klitschko, the head of UDAR (Punch) political party, nationalist Svoboda (Freedom) party leader Oleg Tyagnybok and leading opposition figurehead Arseniy Yatsenyuk.

Meanwhile, Ukraine's President Viktor Yanukovyck told Al Jazeera that Tymoshenko could be pardoned but only after "the legal proceedings of the criminal case that Mrs Tymoshenko are subject to are over".