NAIROBI, Kenya (AP) — A strike delayed flights at Kenya’s main airport Monday as workers demanded better pay and working conditions.

Kenya Airways, the east African country’s main airline, issued a travel advisory, urging customers to check their flight status before heading to the Jomo Kenyatta International Airport in Nairobi. The statement also said air traffic control operation delays were affecting departures and arrivals and flight schedules would have to be adjusted.

“Passengers are advised not to proceed to the airport without a confirmed flight status,” the airline said.

Thousands of stranded passengers could be seen sitting outside the airport. Some families told The Associated Press their relatives were stuck inside terminals.

A passenger who declined to give their name and details said they had been “waiting at the airport for six hours,” hoping to finally board a plane.

Trent Bryski, a Canadian passenger, said no information had been given yet his visa had expired.

“Actually we are not supposed to be out here because our visa says we have left, so they gave us a special letter, and we don’t know when we are leaving again,” he said.

The Kenya Airports Authority said it took contingency measures to minimize disruptions as it attempted to resolve the ongoing strike, stressing its openness to constructive dialogue.

Airport workers issued a strike notice last week after authorities failed to implement part of an agreement with the union. The agreement demanded better labor conditions and increased pay and benefits.

The airport is a major transport hub for regional and international travel.