LONDON, June 10 (Reuters) - Upmarket online fashion retailer Net-A-Porter.com reported a more than 230 percent rise in 2008 profit after developing strong relationships with luxury fashion houses and new and existing clients.

"Sun Chic-ers", dressing for summer sun at Net-A-Porter

The company said it had benefited from exclusive collaborations with designers including Alexander McQueen and RM by Roland Mouret. It said much of the growth had also come from a strategic approach to buying.

Profits before tax for the year ending January 2009 rose 234 percent to 10.1 million pounds ($16.55 million), while turnover was up 47.8 percent to 81.5 million pounds.

The group said it was drawing on average 6,500 new customers to the site every month and had redesigned its website and back office to cope with the increased demand.

"I am thrilled with this year's results which continue to show that people are turning to the Internet as a viable -- and in many cases, preferred -- shopping and media destination," founder and Chairman Natalie Massenet said in a statement.

Many UK retailers have struggled over the last year as consumers cut back on spending during the recession. But online retailers such as Net-A-Porter.com and the cheaper ASOS (ASOS.L) have bucked the trend.

(Reporting by Kate Holton; editing by Elaine Hardcastle)