Labor frontbencher Katy Gallagher has denied that she is a citizen of Ecuador as the dual citizenship fiasco continues to roil federal politics.

Key points: Katy Gallagher's mother was a British citizen, born in Ecuador to British parents

Katy Gallagher's mother was a British citizen, born in Ecuador to British parents The 2008 Ecuadorian constitution says anyone born in the country, and their descendants, are citizens

The 2008 Ecuadorian constitution says anyone born in the country, and their descendants, are citizens Senator Gallagher claims this did not apply when her mother was born so she is not, and never has been, an Ecuadorian citizen

The Daily Telegraph has obtained a passenger entry card that shows Senator Gallagher's mother was born in Ecuador.

The newspaper said Senator Gallagher may have inherited Ecuadorian citizenship from her mother under the South American country's constitution.

But Senator Gallagher, Labor's spokeswoman for small business, issued a blunt denial late last night, insisting she is not under a constitutional cloud.

"I am not and had never been an Ecuadorian citizen," she said.

The senator said the ALP thoroughly investigated her family history before she stood for parliament.

"As part of the ALP vetting process, I disclosed that my mother was a British citizen, born in Ecuador to British parents, who were temporarily working in Ecuador," she said.

"The circumstances of my mother's birth and citizenship were investigated. As a result of these investigations it was determined that I had not obtained Ecuadorian citizenship by descent from my mother."

The 2008 Ecuadorian constitution says anyone born in the country is an Ecuadorian — as well as their children, grandchildren and great-grandchildren.

But Senator Gallagher said the 2008 constitution was not in effect when her mother was born and did not apply retrospectively.

Seven federal parliamentarians have already been caught up in the dual citizenship crisis: crossbench senator Nick Xenophon, the Nationals' Matt Canavan, Barnaby Joyce and Fiona Nash, One Nation's Malcolm Roberts and the Greens' Scott Ludlam and Larissa Waters.

No ALP parliamentarians referred to High Court

All have asked — or will ask — the High Court to determine if they can continue to sit in Parliament.

The High Court held its first hearings on five of those cases last week, with the Chief Justice ordering the matter be heard in Canberra from October 10-12.

So far, no Labor parliamentarians have been referred to the High Court — although some Opposition MPs have resisted demands they release documents to prove they have renounced citizenship from other countries.

Both Greens senators resigned when they realised they were dual citizens, while Senator Canavan stepped down from Cabinet.

But Mr Joyce and Senator Nash have both declared they will stay in Cabinet because they are confident the High Court will find they are eligible to sit in Parliament.

Senator Xenophon has also said he will continue to sit in the Senate while the High Court hears his case.