Japan Airlines Co. halted sales of steeply discounted tickets for domestic flights after demand overwhelmed the carrier’s website.

“We are currently investigating and working to restore the connection,” the Tokyo-based company said in a statement Thursday, asking customers to refrain from accessing the website until the problem is resolved.

Demand for travel within the island nation is picking up, with the government planning to downgrade the coronavirus to the same category as seasonal influenza in May. Hokkaido-based carrier Airdo Co. and ANA Holdings Inc. have also unveiled plans to sell discounted flights over the next few months.

JAL’s website was hit around midnight on Thursday, when the airline began its “JAL Smiles” campaign offering domestic one-way tickets at a flat rate of ¥6,600 ($48) for adults and ¥4,950 yen for children, during April through June. The offer had been set to run through March 14.

A Japan Airlines spokeswoman said customers can still reserve flights that aren’t part of the campaign via app and by phone.