ONS estimates show 729,000 people aged 16 to 24 were unemployed between January and March, up from 620,000 a year earlier, while the youth unemployment rate rose from 14.2% to 16.2%.
The ONS said there were 2.5 unemployed people per vacancy across the UK between January to March.
Claimant count figures from ONS/Nomis show the rates of young people claiming unemployment-related benefits in April.
In Hastings, 625 people aged 18 to 24 were claiming unemployment-related benefits, equivalent to 10.7% of residents in that age group – the highest rate in East Sussex.
Thanet had the highest rate in Kent at 11.7%, Crawley was highest in West Sussex at 7.5%, and Spelthorne was highest in Surrey at 5.9%.
The overall South East rate (4.9%) was below the UK average at 5.7%.