The British woman who was attacked with acid in the Algarve on Saturday is a rep who worked for TUI.
Eleanor Chessell, 29, is in a serious condition in a Lisbon hospital after suffering burns to more than a third of her body.
The attack happened near a supermarket in the village of Alvor, close to the four-star Alvor Baia Hotel where she was working.
Thomson and First Choice said they were saddened by the attack and gave assurances to customers.
"Our resort team are fully supporting our colleague and are co-operating with the police investigation currently taking place by local police,’ said a statement.
"We would like to reassure our customers that this is an isolated incident and situations like this are extremely rare."
Some reports say police are believed to be trying to locate the victim’s ex-boyfriend.
