"Zero hour for the liberation of Falluja has arrived. The
moment of great victory has drawn near and Daesh has no choice but to
flee," he said.
Iraq's military has already warned civilians to leave the town.
Falluja was the first city to fall to IS in 2014 and is one of
only two of its remaining strongholds in Iraq.
The Iraqi military told state TV that those who could not flee
should raise a white flag above their homes.
The military, police and volunteer fighters virtually surround
the city, about 65 km (40 miles) west of Baghdad.
The Baghdad-based pro-Kurdish news website Shafaq said on Sunday
that close to 20,000 police troops had arrived on the outskirts of Falluja
ahead of the expected assault.
Iraq's military seized the nearby city of Ramadi from Islamic State in December.
A former US ambassador to Iraq predicted the Falluja operation
would take some time.
"I think Haider al-Abadi has taken the advice of many of
his American advisers, which was not to rush into this thing," Christopher
Hill told BBC Radio 5 live.
"So they're being very deliberate, very careful and so I
think there's some good reason for optimism that ultimately this will be
successful."
The
Iraqi army, police and irregular forces virtually surround Falluja and have
been heavily reinforced in preparation for an assault on several fronts that
military sources say could begin in the next day or so, and which they expect
to last two or three weeks.
That
may be optimistic, given the many weeks it took earlier this year to take full
control of Ramadi, another city further to the west.
Falluja
has been held by the militants of IS much longer, for nearly two and a half
years, and has withstood a massive battering by government shelling and
bombing.
But
Iraqi military sources believe the number of militants there has been cut
roughly in half and that the battle for Falluja will be a lot less tough than
it was for Ramadi.
Should IS lose Falluja, it would leave the northern city of
Mosul, Iraq's second-largest city, as its only Iraqi stronghold. It continues
to hold large parts of territory in neighbouring Syria, though that amount is
also dwindling. Last month, the United Nations and Human Rights Watch warned
civilians still living in Falluja were in danger of starvation.
The World Food Programme said stocks were dwindling as
government forces trying to recapture the city had cut supply routes, and IS
had stopped people from leaving.
