A company in the United Arab Emirates said an employee was fired and deported after he allegedly celebrated the mass killing of Muslims in New Zealand last week.

At least 50 people were killed and dozens wounded by a lone gunman at two mosques in Christchurch on Friday in what is the country's worst modern mass shooting.

Australian Brenton Tarrant, 28, a white supremacist who was living in New Zealand, was charged with murder on Saturday.

"Over the weekend, a Transguard employee made inflammatory comments on his personal Facebook account celebrating the deplorable mosque attack in Christchurch, New Zealand," security company Transguard said in a statement on Tuesday.

"We have a zero-tolerance policy for the inappropriate use of social media, and as a result this individual was immediately terminated and turned over to the authorities to face justice," Managing Director Greg Ward said.

The company said the employee was deported by the UAE government.

Transguard, an Emirates Group brand, did not disclose the alleged comments. The name, nationality, and position of the employee were also not disclosed.

UAE government officials did not immediately respond to requests for comment.

An Emirates spokeswoman said the company had nothing to add to the Transguard statement.

The UAE has condemned the attack and expressed its condolences to the victims' families and to New Zealand.