7-Eleven is getting some kudos from its Japanese parent company and not-too-subtle encouragement to step up efforts to sell more fresh and fast food.

Seven & I Holdings Co. Ltd. said Thursday in a recording to review results that its Irving-based 7-Eleven U.S. operation reported the highest operating income in its history and posted a 3.4% comparable store sales increase in the first quarter. And while fresh food and the company's 7-Select private brand products drove the improved results, the Japanese parent sees more potential.

"The development and improvement of fast food items is important and something which we will be doing going forward," Seven & I said in its first-quarter report. "We also believe changing public perceptions of 7-Eleven in the United States to be important. In order to change public perception when it comes to buying food products at 7-Eleven, like is common in Japan, we will be strengthening store cleanliness and improving customer service."

The parent company also said it plans to continue store renovations in the U.S.

For 7-Eleven's U.S. stores, the sales momentum continued this spring, with same-store sales up 5.2% in April and 2.8% in May, the company reported. 7-Eleven executives in Irving didn't respond to a request for more information.

Also, its 7-Rewards loyalty program and the introduction of 7-Eleven private branded products into Sunoco stores increased profit margins. 7-Eleven completed the $3.3 billion purchase of 1,030 convenience stores in 17 states from Dallas-based Sunoco in the first quarter of 2018.

In the deal, 7-Eleven also ended up with the Laredo Taco Co. brand, and it's testing it in its lab store that opened in March in Oak Cliff.

That store is also testing a scan and pay system that shoppers use with their smartphones. Seven & I said on the recorded earnings call that it's part of the retailer's "personnel-saving efforts" and "designed to increase profitability."

7-Eleven's U.S. operating income of $161 million was up $31 million from a year ago, Seven & I said, adding that the U.S. business allowed the Tokyo-based retailer to post profits that exceeded its guidance for the three months ending in March.

Seven & I, which in addition to convenience stores also operates supercenters and specialty stores in Japan, reported a first-quarter profit increase of 21.5% to $482 million. Total revenue declined 0.2% to $14.76 billion.

Twitter: @MariaHalkias