Tesco has launched a new range of local milk into 650 stores just six weeks after unveiling plans to do so.

It is a key part of the retailer's shock initiative to hand an extra £25m back to dairy farmers from its own pocket. Called Localchoice, the milk is only available in four-pint bottles to begin with, priced £1.23, or 8p more than the standard four-pint price of £1.15.

"It's been tremendous effort to get the launch out this week," said Kari Daniels, chilled food category director. "Four pints is the most popular size, and we're anticipating strong family take-up, but we may have to extend the format depending on demand."

The milk is supplied by 126 members of the Dairy Farmers of Britain co-op for 23ppl. They are arranged in groups relating to the 14 English and Welsh counties and regions in the range. Initially Localchoice is only going into Tesco Extra and superstores, but there was potential to increase production, Daniels said.

"We're only sourcing from a small number of producers, so we just need to monitor take-up; all the logistics are there for an increase."

Daniels admitted fewer than half the 14 different milks were fully local - most would be processed outside the county. DFB has seven different milk processing plants - more than any other British milk supplier - but not enough to cover every area of England and Wales. "It's as local as milk can be," added Daniels. "That capacity is the reason we partnered with DFB on this."

Tesco is also looking at launching a Northern Irish milk with Dale Farms and a range of up to three local milks in Scotland, with existing supplier Robert Wiseman.

In return, 12 of Tesco's dairy farmers are looking at improving the standards of all the retailer's milk suppliers.

"Over time, the criteria for our milk producers will change," said Daniels. "We want to raise welfare by stopping them exporting live calves."

Instead, the retailer wants male dairy calves reared for beef in the UK.