Copper prices maintained a positive tone in late business on Thursday, with upbeat labour market data in the United States and indications of brighter demand prospects outweighing lingering concerns about sovereign debt in the euro zone.

Copper for May delivery HGK0 on the New York Mercantile Exchange's COMEX division ended up 3.50 cents at $3.3805 per lb, near the upper end of its $3.3205 to $3.3870 session range.

On the London Metal Exchange, benchmark copper for three-months delivery CMCU3 closed at $7,435 a tonne in official rings from a close of $7,375 on Wednesday.

Lead CMPB3 was at $2,077 from $2,026, with LME data showing lead stock rose 400 tonnes to 172,000, their highest since 2003. Aluminium MAL3 was at $2,222 from $2,224, zinc MZN3 was at $2,245 from $2,211, while tin MSN3 was at $17,600 from $17,500.

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