The Australian Federal Police has denied seizing a computer and phones belonging to relatives of East Timor's finance and resources ministers.

AFP officers charged Palmera Pires at Darwin Airport on Friday for allegedly trying to bring in more than $20,000 undeclared in her baggage.

Ms Pires is the sister of finance minister Emilia Pires and resources minister Alfredo Pires, and also the director of the East Timor Development Agency.

She was travelling with her 12-year-old goddaughter, elderly mother and an assistant.

The group was stopped by Customs on Friday, and issued with an $850 infringement notice for failing to declare the currency.

Ms Pires has shown the ABC several receipts that appear to back up her claim that several mobile phones, sim cards and memory sticks were also confiscated as part of a "pending investigation".

Ms Pires says the AFP and Customs officers did not tell her why the devices were seized.

Seized: A Customs receipt for several goods including an iPad and two mobile phones. ( Supplied )

"They have the right and we don't need to know the reason they kept saying that. They have a right to do anything," she said.

The AFP has confirmed officers and Customs officials questioned three people at the airport, but denies any personal belongings were seized.

"The AFP did not seize any currency or material in relation to this matter," a spokesperson said.

"A 50-year-old woman was issued an infringement notice of $850 for failing to declare the movement of $20,000 or more into Australia.

"A 74-year-old woman and a 42-year-old woman were cautioned for failing to report the movement of $10,000 or more into Australia."

Claims incident was politically motivated

Ms Pires says she believes the airport confrontation was politically motivated.

"I think that the only crime was to have a brother and a sister who are ministers and they are fighting for what is right for Timor-Leste," she said.

"What I've been treated, what my mother, my helper and my godchild, who is the first time in Timor-Leste, we didn't have to go through that and then taking the only phone and communication that we have with our family [from us]."

Ms Pires says they have been traumatised by the experience.

"Last night we all just slept in the living room because they are too scared, we think someone is going to come here and break it in," she said.

The airport incident comes as East Timor attempts to have a $40 billion oil and gas treaty it signed with Australia quashed in The Hague following spying allegations.