Officials had previously predicted their operation against guerrillas of the Free Aceh Movement (GAM) would be wound down in less than six months.
Indonesia sent thousands of paratroopers to the restive area on 19 May after peace negotiations collapsed.
“If the martial law status in Aceh is reduced, perhaps the results we have already attained could not be continued, especially related to how we will face the 2004 general election,” General Endriartono Sutarto told a legislative committee, according to AFP.
He was quoted in the Indonesian daily newspaper Kompas.
“Because of that, TNI (armed forces) strength in Aceh will be maintained until the condition is judged peaceful and the people's everyday lives can go on normally,” he added.
Aceh is rich in oil and liquid natural gas
The military operation against GAM, who have been waging a separatist war in the north western tip of Sumatra for the past 27 years, is the country’s largest since former President Suharto invaded East Timor in 1975.
Aceh is rich in oil and liquid natural gas (LNG). ExxonMobil, a company rarely spooked by civil strife quit pumping from its plant in the region on 9 March this year.
Rebels have fired at its planes and set land mine ambushes for its vehicles.
Indonesia is the world’s largest exporter of LNG and exports from Exxon’s Arun plant alone were expected to fetch about $1.4 billion this year.
GAM's chief spokesman, Sofyan Daud, told AFP that any extension of Indonesian military operations in the province would lead to an increase in human rights abuses.
He added that his troops could withstand months more of fighting.
"816 GAM rebels have been killed in the past three and a half months"
Human Rights Watch warned of violations in May, saying in a report “the declaration by the Indonesian government of a state of military emergency for Aceh, and the start of a military campaign, sets the stage for gross human rights violations".
“Given Indonesia's past abuses in Aceh, there is tremendous potential for civilians to be targeted in the violence,” the report added.
The military said on Wednesday it had killed 816 GAM rebels and seized 344 guerrilla weapons during the start of the operation.
A further 1,700 rebels had been arrested or surrendered, AFP reported.
In a separate incident, Indonesian Vice President Hamzah Haz on Wednesday called America the “terrorist king”. His remarks are at odds with Jakarta’s stated support for the US-led “war against terror.”
“Actually, who is the terrorist, who is against human rights? The answer is the United States because they attacked Iraq. Moreover, it is the terrorist king, waging war," Antara news agency quoted Haz as saying.
There has yet to be a US reaction to the well-known firebrands comments.