A passenger reportedly spat at a member of staff on board a Translink bus that was travelling in the Rosetta area of east Belfast on Saturday night.
Police are investigating the incident which is believed to have occurred at St John’s Avenue at around 11pm.
Police say this was a ‘disgusting and despicable’ incident.
“We would appeal to anyone who witnessed the incident to contact police on 101, quoting reference number 1593 28/03/20. Alternatively, information can also be provided to the independent charity Crimestoppers on 0800 555 111 which is 100% anonymous and gives people the power to speak up and stop crime,” said a spokesperson.
The incident comes as the threat of COVID-19 increases across Northern Ireland.
Meanwhile two members of the PSNI have been confirmed as having coronavirus, the Chief Constable has said.
Simon Byrne said other staff are in self-isolation to minimise the spread of the virus.
“We are the third lowest police service anywhere in the UK for absence at work and can reassure the public that we remain committed to ensuring the safety and security of all our communities.
“We are confident we have tried and tested plans in place that would stand up to the Government’s reasonable worst case scenario and have a full range of business continuity plans to protect and maintain essential services.
“These are going to be extremely challenging times for the police service and our partner organisations and we are all working together to support the response to COVID-19 Coronavirus and to ensure we have in place proportionate, appropriate and efficient procedures to address and respond to any challenges presented to the police service by COVID-19, he added.