Check-in systems at various airports faced issues on Wednesday morning due to a system outage, according to a source. The source added that some flights have been delayed due to the issues.

"Microsoft Windows reports major service outages globally. IT services/ check in systems at airports are impacted," as per a message for the passengers at the Varanasi airport. While the tech major denied any such outage.

According to the message, airlines have implemented manual check-in and boarding procedures. At least four airlines -- IndiGo, SpiceJet, Akasa Air and Air India Express -- have been affected, it said.

However, Microsoft in its response to media queries said the passenger message at the Varanasi airport was "...factually incorrect and no outage reported on Windows."

"Some domestic airlines are currently experiencing operational challenges, which may lead to delays or schedule challenges. Our on-ground teams are diligently working with all stakeholders to ensure a seamless and efficient passenger experience," DIAL said in a post on X at 7.40 am.

Specific details could not be immediately ascertained.