World oil prices extended gains this week as it dropped below $87 in Asian trade as demand concerns remained intact due to European and US economic crisis. Benchmark oil for October delivery was down $1.11 at $86.85 at midday Singapore time in electronic trading on the New York Mercantile Exchange. Crude dropped $1.44 to settle at $87.96 on Friday. In London, Brent crude for November delivery was down 50 cents at $111.72 on the ICE Futures exchange. In other Nymex trading for November contracts, heating oil fell 2.7 cents to $2.99 per gallon and gasoline futures slid 2.1 cents to $2.74 per gallon. Natural gas for October delivery fell 0.6 cent to $3.80 per 1,000 cubic feet. Analysts said the black Gold is likely to extend losses during the day as investors are still worried over demand concerns as debt crisis in the eurozone and the weak US economy continued to hit oil markets. Meanwhile, the greenback strengthened against the euro as it fell to $1.3666 from $1.3794 during last week. A stronger dollar makes commodities such as oil more expensive for investors with other currencies. Analysts added that investors are now waiting for the outcome of an US Federal Reserve meeting that may hint at further measures to bolster the world''s biggest economy.