Jailed Kiwi Sharon Armstrong knew she was carrying a secret parcel in a hidden compartment in her suitcase - but she is adamant she had no idea the parcel contained drugs.

The surprise revelation came in an exclusive interview with the Herald on Sunday in Buenos Aires' Unidad 31 prison.

Armstrong's faint hopes of an early release from prison were dashed when Judge Daniel Petrone confirmed he would proceed with a full investigation at a private court appearance.

In the interview yesterday, the former Wellington civil servant said she was tricked into believing she was taking a top secret business contract to a man in London that she had been dating online for six months.

"I know I have been incredibly stupid," she said. "But I was in love with him.

"He said that it was documents and a contract. I don't know any more about it and I didn't ask. I just thought it was really important and that the contract was worth a lot of money.

"I know I am innocent, my family and friends know I am innocent. If you ask them, they will say my biggest fault is that I am too trusting."

Armstrong refused to say how she came into possession of the suitcase, but it is understood the switch was made with the case she brought from New Zealand just before she attempted to board a British Airways flight to London on April 13.

Armstrong said she didn't notice the 5kg of cocaine, which would have weighed significantly more than papers.

Staff at the Hotel Caoca where she stayed for a week said she left with the same suitcase she had arrived with.

She was apparently instructed by the traffickers to say that she had packed her own bag to avoid suspicion from Customs officers.

At Thursday's court appearance, Armstrong and her government-appointed lawyer, Laura Vouilloud de Fassi, were joined by a representative from the New Zealand Consulate and several translators.

After returning to prison, Armstrong read a statement.

"I really need to say this," she said. "Thank you for your concern, but I need to refrain from discussing my situation, primarily because of the pending court case.

"It's just some advice that I have been given."

Investigators will take at least four months to go through all the evidence.

The charge of attempted trafficking carries a prison sentence of between six and 16 years.

Armstrong's Australia-based daughter and sister are making preparations to fly to Argentina. An international manhunt across two continents has so far failed to turn up any trace of the traffickers who gave the suitcase to Armstrong.

Part of the investigation will look at whether the traffickers were connected to any of the two Colombian and four Mexican drug cartels that control most of the drug trade in Argentina.

About 700 "drug mules" have been caught trying to leave Argentina with cocaine since 2006, but fewer than a dozen of the masterminds behind the smuggling operations have been apprehended, an official said.