* Vacancy rate in top 20 UK retail spots 2.55 pct in Aug.
LONDON, Sept 19 (Reuters) - Vacancy rates across the UK's top 20 shopping malls and high streets fell to a 10-year low in August, helped by strong demand for super-prime space from international and UK retailers, data from property consultancy DTZ showed.
The average August vacancy rate across retail locations such as Capital Shopping Centres' Trafford Centre and Hammerson's Bullring mall fell to 2.55 percent in August, against 3 percent a year ago, DTZ said on Monday.
In London, there were effectively no vacant units on Oxford Street, Bond Street and Regent Street, as well as in Westfield Group's Westfield London shopping mall, DTZ said.
"International retailers currently acquiring space in the UK, such as Forever 21, Hollister and Victoria's Secret, are focusing on the top ten or twenty locations before moving on to continental Europe and Asia," DTZ's Head of UK Retail, Hugh Radford, said.
"We don't see the number of locations that international retailers are targeting increasing in the medium term."
Top global retailers are paying increasingly high rents and premiums to take space in London's prime shopping streets, forcing an expansion of the UK capital's shopping district as other secondary locations grapple with high vacancy rates.
Such secondary locations may have to shrink to adapt to reduced current and future demand, Radford said, and may see some shops converted to other uses like offices and residential. (Reporting by Brenda Goh)