Jan 18 (Reuters) - European countries have criticised the arrest of Russian opposition politician Alexei Navalny on his return home after being poisoned and some have called for European Union sanctions against Moscow.

Here are some of the measures which the EU might consider taking, based on proposals mooted in previous cases when the West considered sanctions against Russia.

TARGETED TRAVEL BANS/ASSET FREEZES

Western countries may consider targeted sanctions on Russian individuals deemed to have been involved in Navalny's arrest and any decision to jail him.

The EU and the United States already have travel bans and asset freezes in place against Russians accused of responsibility for human rights abuses, including Navalny's poisoning and the 2009 death in jail of Sergei Magnitsky, a lawyer arrested after accusing Russian officials of tax fraud.

ECONOMIC SANCTIONS

The EU already has sanctions in place on Russia's energy, financial and arms sectors, and a ban on doing business with Crimea, over Moscow's seizure of the peninsula.

Toughening such sanctions would require unanimity among the EU's 27 member states. While some, such as Poland, are open critics of Moscow, others, such as Hungary, might be less willing to back tougher economic sanctions against Russia.

NORD STREAM 2

Berlin faces calls to take punitive steps over the Nord Stream 2 pipeline that is being built to carry natural gas directly from Russia to Germany. Most of its construction is complete.

Some EU countries say the pipeline will undermine the traditional gas transit state, Ukraine, and increase EU reliance on Russia for energy.

The United States, keen to increase shipments of liquefied natural gas to Europe, opposes the pipeline and this month told EU companies it suspects are helping build Nord Stream 2 that they face a risk of sanctions. Zurich Insurance Group decided to drop out of the project following the call.

Germany has supported the project so far, arguing it is a commercial venture, and government spokesman Steffen Seibert said on Monday that had not changed.

TURKSTREAM

TurkStream is another pipeline project, which will carry Russian natural gas to southern Europe through Turkey.

Russia started gas exports via TurkStream to Turkey last year and supplied the first gas via Bulgaria to Serbia in early 2021. Any action considered over TurkStream would be intended in effect to suspend its further expansion to Europe.

The Russian foreign ministry has said that sanctions threats against pipelines amount to "political pressure" and "unfair competition".

SOVEREIGN DEBT

Another possible response that might be considered is limiting foreign investors' ability to hold Russia's sovereign debt.

OFZ bonds are an important source of cash for state spending.

DISCONNECTING RUSSIA FROM SWIFT

Another possible step that could be considered is disconnecting the Russian financial system from global SWIFT interbank payments, which would make international financial transactions nearly impossible.

Andrey Kostin, chief executive of Russia's second largest bank, VTB, has said such a move would be comparable to a declaration of war.

($1 = 75.3548 roubles) (Reporting by Moscow bureau and Gabriela Baczynska in Brussels; editing by Andrew Osborn and Philippa Fletcher)