Over 2,000 people gathered in Kiev on Saturday to protest against the regime of President Viktor Yanukovych and express support for jailed ex-premier Yulia Tymoshenko, who has been moved to a hospital.

The protestors called their rally an "opposition congress" that gathered several opposition parties on a central square in the capital in support of Tymoshenko, who is serving a seven-year jail term after a disputed verdict.

Yulia Tymoshenko, Ukraine's imprisoned former prime minister, was moved Wednesday from jail to a hospital for treatment of a severe back condition under the supervision of a German doctor.

The move was likely to allay at least some Western concerns over Tymoshenko's health and handling in prison. Top EU officials and some EU governments have vowed to boycott the European football championship matches co-hosted by Ukraine in June, and Ukraine had to cancel a regional cooperation summit this weekend after most heads of central and eastern European states canceled their visits over the Tymoshenko case.

U.S. Secretary of State Hillary Clinton said Tuesday the United States is "deeply concerned" over the treatment of former Ukrainian Prime Minister Yulia Tymoshenko, jailed on disputed charges.

"The United States is deeply concerned by the treatment of former Prime Minister Yulia Tymoshenko and other imprisoned members of her former government," Clinton said in a statement released in Washington.

At least 27 people were injured Friday in the eastern Ukrainian city of Dnipropetrovsk in four successive blasts that President Viktor Yanukovych called a challenge to the nation.

"There is a total of 27" injured in three explosions in the city of about a million people east of the capital Kiev, said an emergencies ministry official, adding there was no immediate information on the fourth blast.

Ukraine's jailed opposition leader and former premier Yulia Tymoshenko has been on a hunger strike since Friday to protest her treatment by prison wardens and doctors, her lawyer said.

"Yulia Tymoshenko has declared a hunger strike," Interfax quoted Serhiy Vlasenko as saying outside her prison in the eastern city of Kharkiv where Tymoshenko has been jailed since last year on abuse of office charges.

Ukraine's jailed opposition leader Yulia Tymoshenko shunned doctors on Saturday after being moved to hospital for back pain that stopped her attending a new trial for tax fraud.

Witnesses cited by local media said two ambulances and four police cars arrived at the women's penal colony in the eastern city of Kharkiv where she is serving a seven-year sentence and took her away late Friday.

A Ukrainian court Thursday opened new criminal hearings against the jailed opposition leader Yulia Tymoshenko in a case set to further dent the ex-Soviet nation's EU membership hopes.

Tymoshenko faces tax evasion and embezzlement charges relating to her time as head of a state power provider in the 1990s.

Russia's secret service has arrested two men in connection with a plot to assassinate Prime Minister Vladimir Putin after the March 4 presidential elections, Channel One state television said Monday.

The station showed two men who said they were acting on the orders of Chechen warlord Doku Umarov. They said they prepared the attack in the Ukrainian port city of Odessa and were planning to carry it out in Moscow.

A two-headed Central Asian tortoise has gone on show at the natural science museum in Kiev where visitors will be able to observe the different eating habits of each head over the next two months.

"Strictly speaking it isn't a tortoise with two heads, but rather two conjoined tortoises," Yuri Yuravliov, a zoologist, told Agence France Presse.

Energy giants ExxonMobil and OMV Petrom said Saturday they have found gas deposits in the Romanian part of the Black Sea continental shelf, a month after they began explorations in the area.

"The first deepwater well drilled by ExxonMobil and OMV Petrom indicates the presence of natural gas," the two companies said in a press release.