Austria and Slovakia announced they were reinstating border controls Monday, following a similar move by under-pressure Germany which said it could face up to one million migrant arrivals this year.

Berlin's shock move, which struck at the heart of the EU's passport-free Schengen zone, had an immediate knock-on effect and ramped up the pressure on interior ministers holding emergency talks in Brussels later Monday.

At least 140 people were arrested Saturday after violence broke out at an anti-immigration rally in Bratislava attended by thousands of people in protest at EU quotas on migrant numbers, local media said.

The rally, organized by an anti-Islam group called Stop the Islamisation of Europe, drew up to 8,000 people, according to Slovakian media. Police declined to give an estimate.

Three people died and 24 were injured in a bus crash in northern Slovakia early on Saturday, rescuers said.

"Three people died, two are in a critical condition, four suffered serious injuries and 18 had light injuries," emergency service spokesman Andrej Hirjak told Agence France Presse, adding the accident had occurred around 0300 GMT.

Slovak police said Friday the Czech embassy in Bratislava received an envelope containing a poisonous salt, the latest suspect mail targeting Czech officials.

The Slovak anti-crime agency NAKA is investigating the envelope, which contained sodium azide when it arrived Thursday, police spokesman Michal Slivka told AFP.

Slovak President Andrej Kiska on Wednesday threw his support behind the anti-corruption rallies sweeping the country and urged the leftist government to "listen to the dissatisfaction" of thousands of protesters.

The opposition-led demonstrations "are understandable, they are legitimate, I can see the reasons for them," the non-aligned Kiska told parliament.

The Guantanamo Bay prisoners released to Slovakia as part of efforts to empty the controversial U.S. military detention center pose no security risk, the Slovak interior ministry said Friday.

The two men, a Yemeni and a Tunisian, arrived in Slovakia on Thursday after being held at the prison facility in Cuba for more than a decade without charge or trial.

Slovakia's President Andrej Kiska has given his first month's salary to 10 impoverished families, some coping with serious illness, a spokesman said Friday.

"Eight families will each receive bank transfers of 537.60 euros ($721.92). In the other two cases, the president has sent the same amount by money order for those without bank accounts," spokesman Peter Petrus told local media.

Slovaks return to the polls on Saturday to choose their president in a fractious and tight run-off between Prime Minister Robert Fico and political newcomer and philanthropist, Andrej Kiska.

In round one, on March 15, Social Democrat Fico polled 28 percent finishing narrowly ahead of centrist Kiska, who scored 24 percent.

Slovaks voted Saturday in the first round of a presidential election that Prime Minister Robert Fico is poised to win, amid concerns that his leftist Social Democrats could monopolize power in the eurozone country.

Victory for the former communist frontrunner in a pack of 14 candidates would give control of the presidency, parliament and government to the same party for the first time since Slovakia's independence in 1993.

The foreign ministers of Hungary, Slovakia and Czech Republic will visit Kiev on Thursday where they hope to meet with the new government, Budapest said Wednesday.

Kiev's new leaders are due to unveil a unity cabinet on Wednesday afternoon following the dramatic ouster of pro-Russian president Viktor Yanukovych after months of protests sparked by his rejection of an association agreement with the EU.