Walmart Inc raised its annual US same-store sales forecast after beating analysts' estimates on Tuesday, buoyed by customers splurging on back-to-school products from backpacks to clothes after more than a year of online learning.

Sales at US stores open at least a year rose 5.2%, excluding fuel, in the second quarter. Analysts had estimated a growth of 3.69%, according to IBES data from Refinitiv.

Walmart has been one of the beneficiaries of the stimulus checks given during the pandemic, with the latest quarter also getting a lift from President Joe Biden administration's advance child tax credits.

The company said it now expects fiscal 2022 US same-store sales to be up 5% to 6%, compared with the low single digits growth it had previously forecast.

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"We grew market share in US grocery, added thousands of new sellers to our marketplace, rapidly grew advertising businesses around the world," Chief Executive Officer Doug McMillon said in a statement.

Walmart, which reported its biggest online sales growth of 97% last year as people used its quick delivery services to order essentials at the height of the pandemic, said US e-commerce sales rose 6% in the second quarter.

Operating income rose 21.4% to $7.35 billion, while Walmart reported adjusted earnings per share of $1.78.