"Yesterday, following a threat to our store staff, we made the decision to remove some materials that were published in Arabic," an Optus spokeswoman said. "The safety and security of our staff is paramount." Police have spoken to staff at the Casula store and will be monitoring the situation, a police spokeswoman said. Some of the complainants on social media drew a link between Arabic - the official language of more than 20 countries and the native tongue of more than 200 million people around the world - and terrorism. "What's with the Optus, Casula shopping centre advertisement board, not one word or English on it?" read a post on Facebook. "Very poor taste considering the weekends events. Your advertisement people would be looking for new jobs if I was running the show!" Optus explained the advertisements were simply advising Arabic speakers that there were staff members in the store who spoke their language.​

"We also have posters in Vietnamese and Chinese. What happened on the weekend was a tragedy. The poster is in a language that is used by hundreds of millions of people," Optus employee Gen responded. "It is a language that is NOT used by hundreds of thousands here in Australia!! Disgusting Optus!!" one person wrote. "I personally know of 4 people ending their Optus usage based on this outrage. May not sound like a lot, but those 4 are spreading the word as I am, and they are spreading the word and your reputation here in Aus is sliding." But Optus staff turned to Australia's national anthem to defend their advertising strategy.

"We support all cultures as much as we can, just as we would when singing our national anthem: 'For those who've come across the seas, We've boundless plains to share; With courage let us all combine, To Advance Australia Fair,' " Serena wrote on behalf of Optus. Another complainant said migrants should learn English. "This is Australia not islam," the message read. "If these people wish to come to Australia, they should feel obligated to learn English if they are serious about becoming part of the Australian society." But Optus was quick to respond. "Thanks for your feedback. Australia is a country while Islam is a religion," Dan wrote on behalf of Optus. "The language used on the sign was Arabic, which is also spoken by a number of non-Muslim countries."

Optus said the posters translated in English as: "We speak your language. Come to one of these Optus stores and chat to us in Arabic." A spokeswoman for the company said: "Optus' customers and staff come from a range of backgrounds and speak many different languages. "In some communities, we actively promote the bilingual skills of our front-line staff. We recognise that sometimes customers find it easier to understand the detail of a phone plan when it's explained in their first language. "Optus remains committed to minimising and eliminating discrimination through our corporate culture, marketing activities, employment practices and interactions with the community." The posters, which appear in other shopping centres around Sydney, have only been removed from Casula.

Mariam Veiszadeh, the president of Islamophobia Register Australia which reported the Facebook posts, told Fairfax Media: "The outcry over these ads is over the top and disappointing. We need to safeguard our socially cohesive and multicultural society against these misconceptions about Muslims and the Islamic faith."