Thousands of cabin crew workers at British Airways are preparing to strike just a few days before Christmas.

The Unite union, which represents 2,500 BA cabin crew, said a strike could happen as early as December 22, disrupting roughly 50 short and long-haul routes.

Most of the cabin crew members represented by the union work out of London's Heathrow, one of the world's busiest travel hubs.

The vast majority of BA flights, however, wouldn't be affected by a strike. Fewer than one in five BA cabin crew staffers are members part of this particular union.

Unite argues that its members are not paid a decent salary and roughly half of the cabin crew take second jobs to pay the bills. Members have rejected a proposed pay raise of 2%.

"A massive 84% [of workers] said they had experienced stress and depression since joining BA due to their financial circumstances," the union said in a statement.

Related: Lufthansa makes new offer to pilots after strike grounds 4,450 flights

British Airways -- which is owned by IAG (ICAGY) -- said it hopes to resolve this conflict and avoid any disruption.

"We have proposed a fair and reasonable pay increase," it said in a statement.