Iraq's military took delivery of nine American M1A1 Abrams tanks, the last in an order of 140 that it has received over the past two years, the US embassy in Baghdad said in a statement on Wednesday.

The tanks, which were displayed at a demonstration exercise at a military training complex southeast of the capital, are part of Baghdad's efforts to build up its military, which US and Iraqi officials admit cannot secure the country's borders, airspace, or maritime waters.

"The Iraqi Army officially took possession of nine M1A1 tanks at Besmaya Combat Training Centre, Iraq, on August 27," the statement said.

The 140 tanks cost a total of $860 million, $804 million of which was paid by Iraq with the remainder of the cost borne by the US, according to Commander Gary Ross, a spokesman for the Office of Security Cooperation-Iraq, part of the US embassy.

Iraq received the first batch of tanks, which it ordered in March 2009, in August 2010.

The tanks' capabilities and their operators' training was put on display at the Besmaya complex on Wednesday, the statement said.

"This exercise clearly illustrates the growing capabilities of the Iraqi Army," said OSC-I commander Lieutenant General Robert Caslen.

Iraqi Army chief of staff Lieutenant General Babaker Zebari has persistently said that the country's military will not be able to fully defend it until 2020, though US and Iraqi officials insist the armed forces and police are capable of maintaining internal security.

Baghdad has made $12 billion worth of military acquisitions from the US, whose forces pulled out of Iraq in December, notably including the purchase of 36 F-16 warplanes.