Qantas warns that more than 8000 domestic and international passengers will have their flights disrupted tomorrow as customs and quarantine staff at Sydney's international airport are set to stage a protest on Friday

The strike, which is scheduled to take place for an hour at 10a.m. will impact passengers travelling to Melbourne and those travelling to Sydney. Qantas baggage handlers and ground staff will also stop work for one hour at 7p.m. Thursday.

''Tonight it's fewer workers on and a reduced number of flights ... there will be some delays but it won't be the extent we saw in the morning stoppage,'' Community and Public Sector Union (CPSU) national president Michael Tull said.

The strikes are over a pay dispute and will continue through Saturday. The airline has apologized in advance to any passengers who will be affected by the strikes.

"This really couldn't have come at a worse time with passengers trying to get to the AFL and NRL grand finals and many families heading away for the school holidays," Qantas spokesman Olivia Wirth said.

The latest strike has members of the Transport Workers Union (TWU) which involve 3800 staff campaigning against the airline's pay cuts and working conditions.

"We're sorry that the TWU is taking their grievances out on our passengers over a pay dispute," Wirth said in a release today.

The Australian Licensed Aircraft Engineers Association has told Qantas that will strike tomorrow at 6p.m in Melbourne before taking action in Brisbane on Monday. The union said it will continue to strike until mid-December.