New Delhi: Gold and silver registered their biggest single-day decline in 18 months in the bullion market here on Friday on frantic selling by stockists, triggered by a meltdown in global markets.

Gold plunged by Rs 700 to Rs 27,140 per 10 grams, while silver tumbled by Rs 1,700 to Rs 62,500 per kg, following the precious metal's steepest decline in more than three years in overseas markets.

In global markets, gold nosedived by 7.5 per cent to USD 1,723.70 an ounce from its record high of USD 1,913.50 an ounce on Wednesday, the biggest drop since March, 2008.

The trading sentiment was dampened in global markets as some investors offloaded their holdings of the precious metal after CME, the world's largest futures market, increased the margin requirement for futures transactions.

The minimum amount of cash that speculators must deposit for futures trade in gold was raised by 27 per cent per 100 ounces of the shiny metal on the CME.

Stockists in the Delhi bullion market -- which was closed yesterday in support of Anna Hazare's fast demanding a strong Lokpal Bill -- indulged in heavy selling in tandem with melting global markets.

In addition, demand from retailer customers has dried up at existing high levels, which further influenced the market sentiment. In the national capital, gold of 99.9 per cent and 99.5 per cent purity dropped by Rs 700 each to Rs 27,140 and Rs 26,990 per 10 grams, respectively.

Sovereigns lost Rs 300 to Rs 22,200 per piece of eight grams.

Likewise, silver ready plunged by Rs 1,700 to Rs 62,500 per kg and weekly-based delivery shed Rs 1,525 to Rs 62,090 per kg.

Silver coins also tumbled by Rs 3,000 to Rs 68,000 for buying and Rs 69,000 for selling of 100 pieces.