Prosecutors have dropped charges against a Perth mother who was accused of going overseas and leaving her two children home alone.

The 28-year-old woman, who cannot be identified, was arrested in June after she flew into Perth from Bali.

It was alleged that two days earlier she had left her children, aged four and six, at home by themselves.

They were discovered after police were called to the house and entered through an unlocked door.

The children were then taken into state care.

It has previously been reported the woman had told family and friends she had flown out of the country to renew her visa.

In the Perth Magistrates Court today, police prosecutor Sergeant Neil Regan discontinued two charges against the woman of engaging in conduct that may have resulted in harm to the children.

The court was told it had been decided it was not in the public interest to pursue the charges.

Mum, kids not Australian citizens

Sergeant Regan said his client had liaised with child protection, family services and immigration authorities and there were no longer any concerns for the welfare of the children.

He also said neither the woman nor the children were Australian citizens, and they were required to voluntarily leave the country by the end of the month.

The woman's lawyer Oliver Paxman said the WA police made the right decision. ( ABC News: Joanna Menagh )

Sergeant Regan said it was unlikely the woman would receive a custodial sentence if she was convicted, and for all those reasons it was decided to discontinue the case.

Outside the court, her lawyer Oliver Paxman said if the case had proceeded, it could have taken a year or more to be finalised.

"Given this lady's got two young children, is heavily pregnant with a third child, to keep her in Australia for the sole purpose of conducting that prosecution would have cost the State and the Federal Government huge sums of money," he said.

"So we applaud the West Australian police for making a sensible decision."

Mr Paxman said his client was relieved by the outcome, but the past few months had been extremely stressful for her.

"She did not leave the country to go and a have a holiday in Bali. I want to make that clear," he said.

"She was in a situation where she was under a great degree of pressure. She barely speaks a word of English and did her absolute best to try and arrange care of her children.

"It is an unfortunate set of facts, but she did not knowingly abandon her children for two days while she could go and have a holiday in Bali.

"That is simply not the case."

Mr Paxman said the children were still in state care, but he understood they were going to be returned to his client, in time for them to leave the country.

The woman was assisted in court by a Mandarin interpreter.