The liveweight lamb market has dropped noticeably, with the falls following smaller declines already seen over the month, according to AHDB analysis.
In the week ended 23 June, the NSL GB SQQ fell by nearly 43p on the previous week, to 255.81 pence per kg.
Prices were still well above the level seen in the same week in 2020 though (+29p/kg), and remain high for the time of year, AHDB explained.
Larger falls came towards the end of the period, with prices on Wednesday 23 June down by 57p on the week at 230.58p/kg.
Prices fell as numbers coming to market rose, meaning there were more plentiful supplies during the week, it added.
The number of lambs coming through GB auction markets was 8% higher than both the previous week and the same week last year, at 97,700 head.
Deadweight lamb prices also fell sharply in the week ended 19 June, with the GB NSL SQQ losing nearly 31p to stand at 634.5p/kg. Prices were still 166p above the same week in 2020.
AHDB senior analyst Bethan Wilkins said supplies were now picking up, and this was contributing to the weakening of market prices.
"Price competitiveness relative to continental prices will also be increasingly important, as around this time we typically start to shift to a net exporting position for sheep meat," she said.
"British lamb prices have been at a premium to those in France in recent weeks, which will be reducing export demand just as it did in April, and French lamb prices have also been falling."
