World oil prices fell again this evening, extending the previous day's plunge after the International Energy Agency decided to tap emergency crude reserves to make up for lost Libyan supplies.

US crude eased ten cents to $90.92 a barrel after plummeting $4.39 on Thursday. In London, Brent crude fell $1.31 to $105.95. It had fallen almost $7 on Thursday.

The IEA sparked a steep sell-off when it announced its decision to release 60 million barrels of crude from strategic oil stocks over the next month, as part of efforts to give the global economy relief from sky-high energy costs.

Even before Thursday's IEA announcement, the market was buckling under the weight of a stronger dollar, spreading global economic gloom and contagion fears arising from the Greek and euro zone debt crisis.

The shock IEA move is intended to replace output from Libya, where a revolt against long-time leader Moamer Ghaddafi has practically halted output.

The 12-nation Organization of the Petroleum Exporting Countries (OPEC) - which pumps 40% of global oil supplies - opted earlier this month to maintain its output levels.