The $6.6 billion bailout of Portugal's largest bank poses a warning for other European banks which are heavily exposed to "fragile" emerging market economies in Latin America and Africa, analysts have cautioned.
The Portuguese government announced late Sunday night that it would spend 4.9 billion euros ($6.58 billion) rescuing Banco Espirito Santo (BES), its largest bank by market cap. Under the plan, BES will be split into a "good bank" named Novo Banco and a "bad bank", which will house BES' exposures to the troubled Espirito Santo business empire.
As well as raising concerns about the stability of Portugal, the rescue also highlights fears about Spanish and Portuguese banks' exposure to emerging markets including Brazil.
In a presentation last month, BES described Brazil as a "consolidated emerging economy with strong prospects, high liquidity and strong ties with Portugal."
However, recent data from Brazil tells a different story, raising fears that shaky banks would not be able to cope with economic shocks from the emerging markets.
Brazil's economy is seen by the International Monetary Fund growing only 1.3 percent this year, down from 2.5 percent in 2013. Inflation is remains stubbornly above the targeted 4.5 percent and industrial production dropped for a fourth straight month in June.
Steen Jakobsen, chief economist at Saxo Bank, said Brazil should be at the forefront of investors' minds when considering other Portuguese banks.
"Brazil is coming off, and as you know, Brazil is a huge part of these banks' earnings," he told CNBC on Monday.
"Brazil has an election (this October); they are going to do nothing. I think every single wind there is in the Portuguese banking system is not a tailwind."
Other analysts have flagged broader concerns about European banks' exposure to the "fragile eight" countries of Brazil, India, Indonesia, Turkey, South Africa, Argentina, Russia and Chile. These are major emerging markets whose economies are judged to be precarious.
According to Fitch Ratings, Banco Santander, Spain's biggest bank by market capitalization, is the more exposed to the "fragile eight" than any other major European bank. Like BES, the bank has strong ties to Brazil, from where around 23 percent of its 2013 profits came. It is also a big player in Argentina and Chile and its net exposure to these countries was equivalent to around 370 percent of Fitch Core Capital at mid-year 2013.
Spain's second biggest bank, BBVA, is also exposed to fragile emerging markets, with a 25 percent stake in Turkey's Garanti Bank and majority-owned subsidiaries in Chile and Argentina.
As for banks in the rest of Europe, the U.K.'s Standard Chartered operates in India and Indonesia, while Barclays is exposed to South Africa through its majority-owned subsidiary, Absa Bank. Italy's Unicredit has operations in Turkey and Russia.
According to the European Central Bank, the bulk of euro area banks' emerging market exposure is to Latin America and the Caribbean and Emerging Europe, with Portugal one of the countries most exposed in relative terms. Others countries with strong ties are Austria, Spain, Greece, the Netherlands and France.
BES was also a player in several ex-Portuguese colonies, including Mozambique, Angola and Cape Verde in Africa and Macau in China.
"There are a number of other banks in Portugal that have exactly the same, if not more exposure to the same area of Africa," warned Jakobsen.
Notably, BES also invested in Libya, acquiring a 40 percent stake Aman Bank in 2010, shortly before the revolution that overthrew Muammar Gaddafi. Violence in the country has worsened in recent weeks, with hundreds killed as rival armed factions battle to gain control of the country.
-By CNBC's Katy Barnato