By Josie Cox 

The remorseless slide in the price of oil is hammering an increasingly broad spectrum of the global financial market, particularly pummeling stocks and currencies of oil-dependent economies, and even driving central banks to action.

The central banks of Russia and Norway each responded to lasting low oil prices Thursday to try and stem the selloff in their currencies. In the Persian Gulf, stock markets saw sharp declines.

The price of Brent crude, which has tumbled a staggering 41% so far this year, hit a fresh five-year low of below $63.90 per barrel on Thursday.

"Prices are forecast to remain pressured for at least two more quarters, " said Barclays oil market economist Miswin Mahesh. He predicts that crude could slip below $60 a barrel in the near term--a level which he says is simply not sustainable for markets in the long run.

Russia's central bank on Thursday hiked its key interest rate to 10.5% from 9.5% and its deposit rate to 9.5% from 8.5%, in an attempt to halt a slide in the ruble. The currency was battered earlier this year by geopolitical tensions and resulting sanctions, but its decline has been exacerbated in recent months by the oil shock, especially after the 12-member Organization of the Petroleum Exporting Countries rejected calls for drastic action in November to cut their output. Around 50% of the Russia's annual budget revenue stems from oil and gas exports.

Elsewhere in Europe, the Norwegian krone fell to a five-year low against the euro Thursday after the central bank cut its key interest rate to 1.25% from 1.5% to combat slowing domestic growth, specifically citing the tanking price of oil.

The krone lost almost 1.5% against the euro after the announcement, to trade just over nine kroner per euro. It has depreciated around 7.4% against the euro since the start of the year. Norges Bank was broadly expected to keep rates on hold; it last cut rates in March 2012.

Norway is Europe's biggest crude exporter, and Norges Bank said in a statement Thursday that "activity in the petroleum industry is set to be weaker than projected earlier."

"The continuing collapse in oil prices now hangs like a bad smell over markets," said Anthony Peters, a strategist at London-based financial adviser SwissInvest, adding that it "creates all kinds of conundrums in the foreign-exchange market."

Tim Ash, head of emerging market research for Standard Bank said that Russia is now "like a rabbit caught in the headlights." The central bank doesn't want to "waste" reserves by propping up the ruble, "and doesn't really want to raise policy rates for fear of pushing the economy deeper into recession."

So as long as oil stays low and sanctions remain, the ruble will continue to feel the strain, he said.

Neil Shearing, emerging market economist at Capital Economics, similarly described oil as a "wild card" for Russia.

"If prices rebound, the ruble is likely to follow suit. If they remain at current levels or fall, the tendency will be toward further ruble weakness," he said.

Société Générale strategists said that they now suggest buying the Turkish lira against the ruble.

Turkey is a big energy importer, to the tune of some $55 billion a year, or 6.5% of gross domestic product, according to Standard Bank. Falling oil should deliver benefits for both the current account and for inflation.

Further afield, stock markets in the Persian Gulf also plunged on Thursday, with traders similarly pointing to oil.

Dubai's market was down more than 5%. The main index in Abu Dhabi dropped 4.7%, Qatar slid 4.3% and Oman was down 4.2%. Saudi Arabia's index, the largest in the region, fell 2.2%.

In Europe, the Stoxx Europe 600 subindex of oil and gas companies was down 0.5% taking its slide so far this year to nearly 18%.

London's FTSE 100 index, a large proportion of which is exposed to the oil and gas sector, fell around 0.8% taking losses so far in December to over 4%.

According to several London-based traders, the recent tumble also inspired the central bank of Nigeria to intervene yet again late Wednesday, selling U.S. dollar to prop up the naira.

The central bank has taken action a number of times in recent weeks. Early last week, the naira slumped to 186.9 versus the U.S. dollar. It now trades just below 180, according to Thomson Reuters data.

Oil and natural gas make up almost all of Nigeria's exports and 80% of government revenue, according to the International Monetary Fund. Last week Nigeria's finance ministry proposed a lower benchmark for the budgeted oil price, suggesting spending cuts.

A spokesman for the ministry of finance said last Thursday that Africa's biggest crude producer is now budgeting for an oil price of $65 per barrel, compared with the previous estimate of $73.

"The country lacks a large fiscal buffer, which would allow it to maintain spending or run countercyclical policies," said Duet Frontier Fund manager Hedi Ben-Mlouka, based in Dubai. As well as Nigeria, Kazakhstan would likely be hit particularly hard too, he said.

On Wednesday, a report by Business Monitor International, a research unit of ratings company Fitch, said that the oil tumble had materially increased the risk of sovereign default in emerging markets, singling out Venezuela and Nigeria as particularly vulnerable.

Chiara Albanese contributed to this article

Write to Josie Cox at josie.cox@wsj.com

Access Investor Kit for Barclays Plc

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=GB0031348658

Access Investor Kit for Barclays Plc

Visit http://www.companyspotlight.com/partner?cp_code=P479&isin=US06738E2046

Subscribe to WSJ: http://online.wsj.com?mod=djnwires