Brent prices maintained their gains in American trade, nearing eight-year highs after the US and EU imposed new harsh sanctions on Russia, triggering concerns of supply disruptions.

Brent spiked hugely by 6.8% to $105.10, after closing down 0.7% on Friday away from 2014 highs at $105.74.

Brent rose 5.1% last week after Russia's direct attack on Ukraine.

The EU imposed new restrictions on Russian banks from using the Swift international payments system and other limitations on the Russian central bank, while closing European airspace against Russian airplanes.

Tensions increased further after Russian President Putin announced putting the nuclear arsenal at the ready in response to the sanctions.

The sanctions raised concerns of potential energy supply disruptions from Russia, with natural gas prices spiking over 30% in the last few days.

Dollar jumped higher in European trade against a basket of major rivals after a hiatus from gains on Friday away from two-year highs, with haven demand propelling the dollar higher once more

The dollar index rose 0.9% to 97.42, after closing down 0.6% in Friday on profit-taking away from two-year highs at 97.73.

The dollar index rose 0.5% last week, the third weekly profit in a row after Russia launched military attacks on Ukraine.

The EU imposed new restrictions on Russian banks from using the Swift international payments system and other limitations on the Russian central bank, while closing European airspace against Russian airplanes.

Tensions increased further after Russian President Putin announced putting the nuclear arsenal at the ready in response to the sanctions.

The sanctions raised concerns of potential energy supply disruptions from Russia, with natural gas prices spiking over 30% in the last few days.

Bitcoin spiked 3% on Monday on track for the first profit in three days as demand rallies on the world's largest crypto currency, amid speculation Russia might use cryptocurrencies for its global transactions. 

At Bitstamp, Bitcoin spiked $1,171.78 to $38,888, after declining 3.7% yesterday.

Bitcoin fell 1.75% last week, the third weekly loss in a row as risk appetite tumbles in the market.

Market value of cryptocurrencies declined $38 to a total of $1.74 trillion with Bitcoin, Ethereum and most major cryptocurrencies rallying.

The European Commission decided to shut some Russian banks from the Swift international payment system to punish the country, in accordance with the US, Britain, and Canada.

As the west imposes new sanctions on Russia, traders are speculating that Russia might use cryptocurrencies to avoid the impact of these sanctions on the economy.

Analysts expect wealthy individuals in particular to use  cryptocurrencies to funnel their wealth outside the official global system.

European stocks declined on Monday after a short correctional hiatus on Friday, on track for 9-month lows, and the largest monthly loss sine late 2020.

Dow Jones Stoxx 600 tumbled 1.8%, after spiking 3.3% on Friday, the first profit in three sessions, away from nine-month lows at 434.05.

Dow Jones Europe index fell 1.6% last week following Russia's attack of Ukraine.

The Stoxx Europe index fell on Monday with most sectors firmly in the red, led by the banking and financial sectors, which tumbled over 6.5% after western sanctions on Russian banks. 

The EU imposed new restrictions on Russian banks from using the Swift international payments system and other limitations on the Russian central bank, while closing European airspace against Russian airplanes.

Tensions increased further after Russian President Putin announced putting the nuclear arsenal at the ready in response to the sanctions.

S&P 500 futures fell 1.5% today after a 2.25% profit on Friday on short-covering from nine-month lows.

Euro Stoxx 500 slid 1.8%, while France's CAC shed 3%, as Germany's DAX tumbled 2.75%, while London's Financial Times shed 1.5%.