JAKARTA, Indonesia -- Indonesia began transferring two Australian prisoners early Wednesday in preparation for the execution by firing squad of nine foreigners and an Indonesian condemned for drug smuggling, as diplomatic squabbles persist over the executions.

The preparations at the execution site have been completed at Nusakambangan Island's maximum-security prison facilities, said Attorney General Muhammad Prasetyo.

Besides the two Australians -- Andrew Chan, 31, and Myuran Sukumaran, 33 -- who have spent the past decade in a Bali prison, Raheem Agbaje Salami, 45, a Nigerian national who was born in Cordova, Spain, and 30-year-old Filipina Mary Jane Fiesta Veloso, were also being transferred.

Prasetyo, speaking in the capital, Jakarta, did not give a date for the executions.

Media outside Kerobokan Penitentiary reported Chan and Sukumaran were taken away in two police armoured vehicles in a pre-dawn operation involving scores of riot police.

Prison authorities had earlier turned away Chan's older brother Michael Chan who attempted a visit. Television footage showed Michael Chan walking away from the prison with his brother's Indonesian girlfriend, who was in tears.

Prison governor Sudjonggo, who goes by a single name, told reporters Chan and Sukumaran did not appear worried as they left the prison.

Sukumaran took several pencils in a plastic bag, clothes, a bible and a drawing book.

"He said: Thank you. Take care of his friends," Sudjonggo said.

The four convicts being transferred, plus two Nigerians and four men from Brazil, France, Ghana and Indonesia will be executed simultaneously by a firing squad on the prison island off Indonesia's main island of Java. It was not immediately known how many have been transferred to the island.

The Nigerians face execution after their clemency requests were rejected by Indonesian President Joko "Jokowi" Widodo last month, said Attorney General's office spokesman Tony Spontana.

They are Silvester Obiekwe Nwolise, 39, and Okwudili Oyatanze, 40, whose clemency was rejected after he was caught running drug transactions from behind bars.

Jokowi has received phone calls from some foreign leaders asking that the executions be cancelled, but rejected their requests. He vowed not to grant mercy to drug offenders because Indonesia is suffering a "drug emergency."

The Indonesian government last week recalled its newly designated ambassador for Brazil, Toto Riyanto, to protest the postponement of the approval of his credentials by Brazilian President Dilma Rousseff amid tensions over the imminent execution of its citizen, Rodrigo Gularte, 42.

Australian Prime Minister Tony Abbott has called on Indonesia to "reciprocate" for Australia's $1 billion aid package after the 2004 tsunami by sparing his two countrymen.

Abbott said he had not spoken to Widodo since the prison transfer order was given Tuesday, but had made his views clear to the president in a conversation last week.

"Right now millions of Australians are feeling sick in their guts at the prospect of execution for these two," Abbott told reporters.

"I've been saying again and again that this is contrary to Indonesia's national interest and it is contrary to Indonesia's best values," he added.

Abbott said he understood by many Australians were threatening to never visit Indonesia, a near neighbour.

"I can very much understand their position and I think there are millions of Australians who feel quite angry at this time at what's happening," he said.

But Abbott said the bilateral relationship must survive regardless of what happened to the pair.

"Let's remember that a good relationship with Indonesia is very important to this country and whatever might happen in the next few days, the relationship with Indonesia must endure and, over time, it must grow stronger," he said.

Indonesia executed six drug convicts including foreigners in January. More than 130 people are on death row, including 57 drug convicts.