East Timor's military chief, Brigadier-General Taur Matan Ruak, has also demanded an explanation from international security forces as to how rebel soldiers were able to attack Ramos-Horta and Prime Minister Xanana Gusmao.
Ruak said there had been "a lack of capacity" shown by international security forces in the country, which include 1,100 Australian and New Zealand soldiers, as well as more than 1,600 United Nations police from 40 countries.
Australia's Foreign Minister Stephen Smith told parliament a full investigation would be carried out and international forces would "take account of what, if any, lessons were to be learned".
Smith said he had also spoken to his Portuguese counterpart, who offered extra assistance from Lisbon for East Timor if required in the wake of the assassination attempts.
In Dili, East Timor's Prosecutor-General Longinhos Monteiro said on Thursday that he had issued arrest warrants for six more people suspected of involvement in the attacks on Ramos-Horta and Gusmao, who escaped injury.
That brought the total number of suspects so far to 24.
"We are giving time for police to execute the warrants. We have 21 days to prepare the dossiers," Monteiro said, after meeting interim president Fernando de Araujo.
The police have not yet arrested the suspects.
The atmosphere in Dili remained calm, following parliament's decision to extend the state of emergency for a further 10 days to February 23.
Arsenio Ramos-Horta said his brother would be taken off ventilators assisting his breathing later on Thursday ahead of another round of surgery, expected on Friday or Saturday.
Surgeons this week said it would be several weeks before the president began to be mobile, and up to six months before he fully recovered after discharge in around a fortnight.
