Citing the danger of new coronavirus strains spreading in Europe, Slovakia tightened border controls on Wednesday as it battles one of the highest coronavirus  mortality rates in the world.

The health ministry said anyone crossing Slovakia's borders will have to self-isolate for 14 days upon arrival and some less frequented border crossings will be closed altogether.

"The new regime on borders is intended to prevent the spread of novel coronavirus mutations," Health Minister Marek Krajci said earlier.

Slovakia on Monday had already begun closing some smaller border crossings with Poland to passengers and goods traffic.

There will be exceptions to the new regime for cross-border workers but a negative PCR test not older than 72 hours will still be required.

Slovakia has registered 23 Covid-related deaths per 100,000 inhabitants in the last 14 days -- the second highest level in the world after Portugal, according to an AFP tally.

Since the start of the pandemic, Slovakia has registered 111 deaths per 100,000 inhabitants, putting it 16th in the world and 10th in Europe.

An EU member of 5.4 million people, Slovakia has borders with Austria, Czech Republic, Hungary, Poland and Ukraine.

The Czech Republic is also experiencing stricter border checks after Germany banned travel from there and from Austria's Tyrol region over a surge in coronavirus variants.