Oct. 17 (Bloomberg) –Copper advanced to a three-week high as base metals gained after Group of 20 finance chiefs endorsed parts of a plan to contain Europe's debt crisis and data showed stronger-than-expected U.S. retail sales.

The metal for delivery in three-month gained as much as 1 percent to $7,619.50 a metric ton on the London Metal Exchange, the highest since Sept. 27. The contract traded at $7,561 as of 10:16 a.m. Shanghai time, after adding 2.4 percent last week. Copper for December delivery on the Shanghai Futures Exchange advanced 0.7 percent to 56,400 yuan ($8,846) a ton.

"The positive news over the weekend led to a broad market rally today, helping to boost copper prices, even as there are signs of relatively weak demand," Xiong Dabiao, an analyst at Minmetals Futures Co., said today.

Group of 20 finance ministers and central banks concluded weekend talks in Paris endorsing parts of the emerging plan to avoid a Greek default, bolster banks and curb contagion, setting an Oct. 23 summit of European leaders in Brussels as the deadline for it to be delivered.

Retail sales grew 1.1 percent in the U.S. in September, according to Commerce Department data on Oct. 14. Purchases rose by the most in seven months, beating a median forecast of 0.7 percent surveyed by Bloomberg, easing concern that slumping confidence and scant hiring will derail the economy.

Managed-money funds held net-short positions, or bearish bets on Comex copper in New York, that increased 80 percent from a week earlier, according to the U.S. Commodity Futures Trading Commission. That left investors with a net-short position of 9,489 futures and options contracts on Oct. 11, the most since June 2009, the CFTC data showed.

Aluminum was unchanged at $2,225 a ton, zinc climbed 1 percent to $1,949.50 a ton, and lead added 0.6 percent to $2,038 a ton. Nickel rose 0.4 percent to $18,950 a ton, and tin advanced 1.8 percent to $22,200 a ton.