ABUJA, Nigeria (AP) — Thousands of travelers were stranded in Nigeria Monday as airport union workers began a two-day strike demanding better conditions.

The strike canceled flights as employees from across seven unions in Nigeria’s aviation industry blocked access to the country's largest airports, in Lagos and the capital, Abuja.

Strikes are common in Nigeria’s aviation sector. Workers say they have poor conditions and airlines are struggling with rising costs and fuel shortages. It is the second union-organized strike this year and comes after failed attempts by regulators and policymakers to appease workers.

Monday's strike came on the heels of the government’s refusal to release recently reviewed aviation working conditions and adjust pay to match Nigeria’s new minimum wage of $65 per month, according to a strike notice issued on the weekend.

Hadi Sirika, Nigeria's aviation minister, did not immediately respond to requests for comment.

So far the delays show no sign of abating. In Abuja, the Federal Airports Authority of Nigeria advised passengers to make contingency plans in order to avoid missing flights and appointments.

The seven labor associations said the strike could be prolonged if authorities do not act on their demands to improve conditions and shelve plans to demolish some of their offices in Lagos.

“Should the warning strike fail to achieve the desired results, an indefinite strike shall ensue,” the unions said in the notice signed by each of them and issued over the weekend.