US outdoor apparel supplier Timberland has decided to boycott garments containing Australian merino wool until the practices of mulesing and live exporting stop.

The company said it would "not knowingly sell products which contain Australian merino wool" in protest against mulesing, which involves farmers using gardening shears to slice chunks of skin and flesh from lambs' backsides - without any painkillers - in an attempt to reduce maggot infestation, and live exporting of sheep.

Timberland, which operates nearly 200 stores globally and makes $1.5 billion annual revenue, joins a widening pool of well-known clothing companies such as the high-profile Abercrombie & Fitch in its protest against the way the wool is sourced.

The company decided to cease using merino wool after five months' worth of talks with US-based animal activists group People for the Ethical Treatment of Animals (PETA).

PETA argues that there are many viable animal-friendly methods available to prevent maggot infestation.

US clothing producer SmartWool recently announced it was signing a seven-year contract worth $30m with New Zealand's wool farmers, to replace trading with Australia.