Tesco PLC, the U.K.'s largest grocery retailer by revenue, said June 15 that fiscal first-quarter like-for-like sales jumped 1.8% year over year, its 10th consecutive quarter of like-for-like sales growth and its best quarterly performance since 2011.

"Our task now is to continue that momentum," CEO Dave Lewis said during a same-day media conference call.

The improvement during the 13 weeks ended May 26 stemmed from Tesco's performance in the U.K. and Ireland, where like-for-like sales during that period climbed 3.5% year over year.

While like-for-like sales in the U.K. gained 2.1% year over year, they were up 3% in Ireland as customers reacted positively to Tesco's more competitive price position. The grocer's performance in Ireland was all the more remarkable because the entire estate was closed for one day in early March due to bad weather.

In the U.K., poor weather also crimped performance, but Tesco said it invested in price cuts to exclusive fresh food brands and continued to focus on the relaunch of more than 10,000 products under its own brand.

The supermarket operator's performance in the U.K. and Ireland contrasted with that in its overseas markets. In Central Europe, like-for-like sales shrank 1%, although Tesco said regulatory changes in Poland and Slovakia masked a strong underlying performance.

In Asia, like-for-like sales dropped 9% as the company stepped back from bulk selling in Thailand.

At wholesaler Booker, which Tesco acquired in March for £3.7 billion after a prolonged battle to secure regulatory approval, like-for-like sales leaped 14.3%.

"We are delighted with initial progress on Booker, and are focused on delivering the synergy benefits that our merger brings," Lewis said in a statement.

In early trading in London on June 15, Tesco's shares were up 5.6 pence, or 2.3%, at 255.4 pence.