Jun 20 - British fashion retailer SuperGroup has seen a marked improvement in trading over the past three weeks and is sticking by its expansion plans, it said on Monday, as it seeks to calm nerves after a plunge in its shares.

Superdry store (SuperGroup)

The company behind the Superdry fashion brand also said it had exchanged contracts for a new flagship store on London's Regent Street.

After floating at 500 pence 15 months ago, SuperGroup shares rocketed as high as 1,899 pence in February as it reported a procession of stellar sales figures.

But results last month for the three months to May 1 -- its fiscal fourth quarter -- showed sales growth slowing to 61 percent from 87 percent the quarter before, prompting a dramatic reversal in its shares which closed at 900p on Friday.

"Trading across the group as a whole is in line with management's expectations," it said in a statement ahead of meetings with investors.

"Within that, retail growth remains approximately at the same level as in Q4 (the fourth quarter) but has seen a marked improvement over the last three weeks and is complemented by strong wholesale growth."

SuperGroup, which runs 61 standalone stores in Britain, said it continued to target 20 store openings a year and to believe it had room for around 150 shops in the UK.

The group also has 73 shops abroad and plans to open around 50 international franchise and license stores this year.

(Reporting by Mark Potter; Editing by David Holmes)