US supermarket group Publix has posted an 8.1% increase in net earnings for the first quarter despite the slowing US economy.

Net earnings were US343.2m, up from $317.6m in 2007. Earnings per share for the period to 31 March were $0.41, compared to $0.38 for the previous year.

Sales saw an increase of 6% to $6.2bn from last year’s $5.9bn. Comparable-store sales for the first quarter of 2008 increased 3.6%.

Despite the group’s strong performance, Publix’s stock still fell to $19.45 a share from its previous price of $20.70 a share. Publix stock is not available for sale to the public and is available only to company employees and members of its board of directors.

“I’m proud that our Publix associates continue to deliver strong operating performance,” CEO Ed Crenshaw said. “Unfortunately, the stock market has suffered from the many challenges facing our economy.”