Kantar Worldpanel said the country's second biggest grocer Sainsbury's posted the lowest sales growth and continued to lose market share.

Sainsbury's, which last month announced plans to acquire no.3 Asda, posted sales growth of 1 percent in the period, behind market growth of 2.7 percent, and its market share dropped 0.2 percentage points to 15.7 percent, according to the Kantar Worldpanel data.

The country's biggest grocer Tesco posted sales growth of 2.2 percent, with sales at Walmart-owned Asda up 2.8 percent, and no.4 player Morrisons posting a 2.9 percent rise.

"The sun shone on the grocery market over the past month with record-breaking temperatures, a bank holiday weekend and Royal Wedding fever all contributing to a bumper period," Kantar's consumer specialist Chris Hayward said on Wednesday.

Sales of BBQ-related foods like sausages and burgers soared, as did demand for sun cream, Kantar said.

(Reporting by Sarah Young, editing by Paul Sandle)