Megan Davies, Matt Scuffham

NEW YORK, (Reuters) – Global banks will face a difficult and expensive process if Russia closes its businesses, experts and banking sources say. This could complicate decisions about whether to withdraw.

Russia’s week-old invasion in Ukraine prompted sanctions and Moscow’s retaliation. This has raised concerns about how long banks will be able to continue.

An anonymous banking source expressed concerns over how Russian banks will navigate the order on rouble lending. They are also considering the risks to their reputations by staying in Russia.

Although banks have yet not announced their exits from Russia, at least one bank with Russian operations is creating an internal team with outside consultants and lawyers to help determine if it might exit.

Last week, Shell and BP, the British energy giants, announced they would leave Russia. It stated that BP has decided to sell its share in Rosneft Russian oil giant Rosneft. This could lead to charges upto $25 billion.

Experts say that it will be harder for banks to manage their finances.

For an oil company, selling off Russian assets is as simple as dropping keys. However, for financial service firms, unilateral departures are not possible,” stated Dan Awrey of Cornell Law School, who specialises in financial regulation.

Banks cannot leave a country unless they have the permission of its regulators or central bank. Experts say they would need to find a buyer willing to accept their loans or other obligations.

Awrey stated that it is impossible to unilaterally withdraw from financial claims and lending obligations. It will be more difficult if there is someone on the other end.

Of particular concern was an order from the Kremlin http://kremlin.ru/acts/news/67886 dated March 1, prohibiting rouble lending and credit to persons of foreign states that commit unfriendly acts, one banking source said.

The source stated that banks would have to consider the consequences of this for their operations. They would also need to determine whether Russia prohibits foreign companies from Russia from accessing rouble-based credit facilities. This would severely impact the ability to do business in Russia. Given the current circumstances, the source asked if foreign banks would be able to continue operating in Russia.

According to two U.S. industry sources, global banks are trying to understand how U.S. sanctions against the Russian Central Bank might affect market plumbing. They are cautious when they find a connection with the central bank. This could make it difficult for global banks to transact in rubles.

One senior bank source said that sanctions effectively scuttled any chance for global banks to sell Russian assets. The only options are to write off assets or wind them down, which, according to the source would be a financial risk.

A banking source stated that one possibility is to see if Russian banks can be sued by their clients if they fail to fulfill commitments.

According to the same source, some banks might consider keeping skeleton operations in Moscow rather than withdrawing completely. This would prevent the need to apply for another banking license, and allow you to start a new business.

U.S. banks that have Russia-related operations refused to comment on the matter or didn’t respond.

Citigroup The most exposed U.S. bank to Russia is (NYSE:), and is currently experiencing the difficulties of leaving.

Last year, the bank declared that it was selling its Russian consumer businesses as part of a larger restructuring. VTB Bank in Russia, the Russian state bank that is under U.S. sanction, was the only buyer publicly identified.

Due to sanctions, it’s unlikely that Citigroup could transact business with another Russian buyer. Analysts and lawyers also say foreign banks won’t be interested in Russian assets currently.

Jane Fraser, Citigroup’s Chief Executive Officer, said Wednesday that it was not possible to predict whether the sale will proceed. Mark Mason, Chief Financial Officer at Citigroup, stated that the bank may have to sell nearly half of its Russian Russian exposure in order to keep it out of bankruptcy.

Two people familiar with the situation told Reuters that Austria’s Raiffeisen Bank International is looking at leaving Russia. This would be the bank’s first European move since Ukraine’s invasion.

After sanctions being placed against Russia in response to its 2014 annexation, U.S. banks already reduced their exposures. However, banks like JPMorgan Chase & Co (NYSE:), Morgan Stanley (NYSE:) Citigroup has continued to support and advise Russian companies, and have staff in Russia.