Oil prices fell Thursday amid volatile trading, as NATO chiefs met over the Ukraine crisis and the European Central Bank announced more rate cuts to boost the eurozone economy.

A modest 900,000 barrel fall in U.S. crude stockpiles, close to expectations, and a sharper drop in gasoline stocks, had little impact overall on the trade.

In London Brent North Sea crude for October dropped 94 cents to $101.83 per barrel.

US benchmark West Texas Intermediate (WTI) for October delivery slid $1.09 to $94.45 a barrel.

Prices have swung sharply this week, Brent between $101 and $104, amid a market unsettled by both economic trends and geopolitical disturbance.

On Thursday the market was mainly focused on the ECB, which surprised with a new round of rate cuts. ECB chief Mario Draghi also unveiled plans for a quantitative easing program, buying asset-backed securities help kick-start credit in the region.

The bank also trimmed its growth forecast for the region to 0.9 percent this year and 1.6 percent next year.

Meanwhile in Britain, leaders at a NATO summit kept up pressure on Russia over its support for Ukraine rebels despite the possibility of a ceasefire deal.

The U.S. warned of more sanctions on Moscow, which is accused of fomenting the secessionist rebellion in eastern Ukraine, and NATO head Anders Fogh Rasmussen said Russia was not showing real interest in peace.