Residents on South Australia's Fleurieu Peninsula have expressed dismay at the number of holidaymakers continuing to arrive in coastal towns, despite advice not to travel this Easter.

Key points: Residents have spotted travellers in towns including Goolwa, Port Elliot, Victor Harbor and Normanville, one local says

Residents have spotted travellers in towns including Goolwa, Port Elliot, Victor Harbor and Normanville, one local says Premier Steven Marshall previously declared travel over Easter was "completely and utterly off"

Premier Steven Marshall previously declared travel over Easter was "completely and utterly off" Police say they will be out in force this long weekend and have increased their presence at border checkpoints

Authorities including the Premier and the Police Commissioner have repeatedly urged people to cancel their long weekend travel plans and not to take unnecessary journeys, to protect the community from the spread of coronavirus.

"This Easter, this school holidays, travel around this state is completely and utterly off. We do not want people heading out," Premier Steven Marshall said on Sunday.

However, Goolwa resident Polly Green told ABC News Breakfast locals in popular south coast tourist towns including Port Elliot and Victor Harbor, and on the other side of the peninsula in Normanville, have noticed a rise in travellers.

She said while it was so far less busy than the typical Easter, a stream of tourists had begun arriving in recent weeks, and the local population was still continuing to swell.

"We've got quite a few hundred here at the moment, which is less than thousands and thousands, but we're very concerned," Ms Green said.

"Going down the beaches, families, a lot of young kids [are] surfing — the locals have been talking about it on social media."

Ms Green said she saw caravans heading into town on Thursday, despite the fact local accommodation was closed.

She said while some of them were ratepayers who owned holiday houses in the area, she urged anyone who did not need to be in the area to stay away.

"The shops were just packed and no-one's taking the distancing rules into consideration, and it's not fair to us," she said.

"It's a bit concerning because we've got such an elderly population here, it's one of the high risk areas.

"We want you to come but just not at the moment."

Goolwa is usually a destination of choice for many over Easter. ( Audience submitted: Erin Jarman )

Coronavirus has so far claimed three lives in South Australia and there have been 428 confirmed cases.

"At the locations people tend to holiday we'll be out in force. We'll have police horses, we'll be using the police helicopter, the police plane, and also drones to monitor areas where we believe crowds are likely to gather," Police Commissioner Grant Stevens said.

"We've also been in touch with most holiday camps and caravan parks.

"People are not welcome in those areas and some shops are refusing to serve people who do not reside in those areas."

Extra police will monitor border control points, "limiting the opportunity for people to visit those well-known holiday areas".

Deliberately coughing at people an 'abhorrent act'

Police on Thursday confirmed 11 people had been fined after a house party in Port Augusta on Tuesday night, after the group repeatedly ignored directives from officers.

"The crowd were forcibly dispersed," Commissioner Stevens said.

"We are prepared to show some tolerance … but where this is a blatant disregard for those warnings, we will take action."

Police will crack down on anyone found to be deliberately coughing to intimidate others. ( ABC News: Eugene Boisvert )

The Commissioner also warned people who spit or deliberately cough to scare others on public transport could be committing an offence.

It follows anecdotal reports of people intentionally coughing near drivers or other passengers to cause distress.

"Any action like that, that is done to cause fear of infection may well constitute a criminal offence," Commissioner Stevens said.

"If those matters are reported and we're able to identify those people we will take action. This is an abhorrent act."