Protesters in tiny ex-Soviet Moldova on Thursday pondered their next move after the authorities snubbed a deadline to call early elections in the latest twist in the country's protracted political crisis.

Demonstrators -- including both pro-European and pro-Russian groups -- issued a Thursday ultimatum for parliament to be dissolved after ratcheting up street protests against rampant corruption among the impoverished state's ruling elite.

Some 10,000 people massed in the Moldovan capital Chisinau on Thursday as tensions in the pro-Western nation flared following the secret midnight swearing-in of a new government.

Lawmakers of the impoverished former Soviet republic on Wednesday approved a new government amid political turmoil, with protestors storming the parliament building and opposition legislators attempting to block the vote.

Moldova's parliament on Thursday passed a vote of no confidence in the pro-EU government and prime minister, Valeriu Strelet, in the tiny ex-Soviet state's latest bout of political instability.

Moldova has been rocked by a political crisis over a $1-billion (910-million-euro) corruption scandal that saw a former prime minister arrested earlier this month amid popular protests.

Some 10,000 people took to the streets of Chisinau, capital of Europe's poorest nation Moldova, to protest over the disappearance of $1 billion (900 million euros) from three banks, police said.

In April, the Central Bank of Moldova discovered that the three banks in question granted loans worth a total of $1 billion, equal to 15 percent of the impoverished ex-Soviet state's GDP. 

Moldova has detained seven people suspected of smuggling uranium-238 on a passenger train from Russia, a highly radioactive substance that can be used to make a dirty bomb, Interpol said on Thursday.

After a nearly year-long investigation, Moldovan police also seized 200 grams (7 ounces) of uranium-238, one kilogram (2.2 pounds) of mercury and 1 kg of "an unidentified radioactive material," Interpol said in a statement.

Pro-European parties in Moldova secured a narrow win Monday over those backing closer ties with former master Russia in a parliamentary election held against the backdrop of the bloody conflict in neighboring Ukraine.

Three parties backing integration with the European Union together won about 44 percent in Sunday's vote, seen as a litmus test for the aspirations of the impoverished and politically volatile country.

Moldova went to the polls on Sunday in a crucial parliamentary election that will help determine whether the impoverished ex-Soviet country pursues integration with Europe or returns to Russia's fold.

Polling stations opened at 7:00 am (05:00 GMT), with voters facing a choice between political parties aiming for membership in the European Union and those that back joining Russia in a customs union.

War-weary Ukrainians pick a powerful new parliament next Sunday set to be dominated by pro-Western and nationalist forces who will determine if President Petro Poroshenko can make peace with the Kremlin while holding on to the separatist east.

But it will be a vote held on a war footing in which millions of ethnic Russians in Ukraine will not be able to cast ballots because their lands have been either annexed by the Kremlin or seized by pro-Moscow militants.

Russia on Wednesday vowed to protect its citizens in the Moldovan region of Transdniestr, warning "those who don't think like us" not to meddle in the pro-Moscow breakaway region.

"There is no need to indulge in any illusions about whether Russia will protect its own citizens," the state news agency TASS quoted Deputy Prime Minister Dmitry Rogozin as saying.

U.S. Vice President Joe Biden pledged new assistance Saturday to ex-Soviet republics Georgia and Moldova aimed at helping them stand up to a resurgent Kremlin and establish closer European ties.

Biden held separate meetings with Georgian President Georgy Margvelashvili and his Moldovan counterpart Nicolae Timofti on the sidelines of Western-backed tycoon Petro Poroshenko's inauguration as Ukraine's head of state.