Factbox-European countries tighten borders

(Reuters) -The European Union is dealing with an increase in legal and illegal arrivals by migrants, prompting some member states to temporarily re-introduce border controls within what is normally a zone of free movement.

The bloc's Schengen rules allow such action "as a last resort" in cases that are deemed serious threats to internal security or public policy.

These countries have reinstated stricter checks:

* Austria introduced checks at its border with the Czech Republic in October, set to last until Feb. 16, 2024.

As of November, it extended border controls with Slovenia and Hungary until May 2024, and since December with Slovakia until Feb. 3, 2024, citing pressure on the asylum reception system, threats of arms trafficking, criminal networks linked to the war in Ukraine, and people smuggling.

* Denmark in August tightened border control for arrivals, including those from Schengen countries, at Copenhagen airport to boost security after incidents of Koran burnings.

It has prolonged checks on the Danish-German land border and in ports with ferry connections to Germany until May 2024, according to an EU commission report.

* France as of November reintroduced controls on its borders with Schengen countries, citing what it called terrorism threats. The controls should last until April 30, 2024.

Interior Minister Gerald Darmanin had announced reinforced security in October at the Belgian border after the killing of two people by an assailant in Brussels.

* Germany announced in September controls on its land borders with Poland, the Czech Republic and Switzerland, initially until Dec. 15 and on Friday extended them for another three months.

Berlin said it needed to respond to an immigration surge and high levels of smuggling.

Berlin has also extended land border checks with Austria until May 2024, citing strains on its asylum reception system, security threats linked to Middle East terrorism, and the war in Ukraine.

* Italy reinstated police checks at its land border with Slovenia on Oct. 21, saying some migrants in transit on the Balkan route could be terrorists, saying they would last at least until Dec. 19. Interior Minister Matteo Piantedosi said in October they would likely be extended into next year.

* Norway, which belongs to the Schengen arrangement but is not an EU member, reinstated border controls in its ports with ferry connections to the Schengen area as of Nov. 12, citing threats to its infrastructure, and from foreign intelligence services.

These controls should last until May 5, 2024.

* Poland has extended temporary controls on its border with Slovakia until Jan. 2, 2024, pointing to migrants' efforts to illegally enter from there.

The government was rocked by a "visas for cash" scandal earlier this year, when the opposition accused it of being complicit in a system where people who paid intermediaries received visas at an accelerated pace without proper checks.

* Slovakia on Nov. 20 approved keeping temporary controls on its border with Hungary until Jan. 22, 2024, saying it was seeking to limit the number of illegal arrivals.

* Slovenia on Dec. 10 extended border controls with Schengen members until Dec. 21 and plans to keep them for further six months after that date. The government cited armed conflict in Ukraine, the Middle East and Africa, and elevated threats from organised crime and terrorism.

* Sweden strengthened checks on its borders in August, giving border police more power including body searches and increased use of electronic surveillance.

The same month, the government raised Sweden's terrorism threat level, saying it had thwarted attacks after Koran burnings triggered threats from Islamist militants.

As of November, it extended the border checks until May 2024.

TIGHTENED BORDERS WITH NON-EU COUNTRIES

* Finland on Dec. 15 is to close its entire border with Russia to travellers for one month, after a short-lived reopening of a few crossings on Dec. 14 saw more than 200 asylum seekers entering the Nordic country.

Helsinki says that since November, Moscow has been transporting more than 900 migrants at different border stations in retaliation for Finland's decision to increase defence cooperation with the U.S., a charge the Kremlin denies.

Asylum can still be sought by people arriving by boat and air, the Finnish government said.

(Compiled by Olivier Sorgho and Stéphanie Hamel in Gdansk; Additional reporting by Elviira Luoma; Editing by Frances Kerry, Milla Nissi and Tomasz Janowski)