Thirty four US troops suffered traumatic brain injuries following Iranian missile attack on US bases, the Pentagon has confirmed.

The strikes were launched in the early hours of January 8 in retaliation for the death of top Iranian general Qassem Soleimani days earlier.

Iran initially claimed 80 US troops had been killed, while the United States said there were no casualties.

On Wednesday US President Donald Trump played down the injuries, saying service personnel had suffered "headaches" in the aftermath.

The attacks on two bases - the Al-Assad airbase in the south and a US-operated base in Irbil in the north - came after Soleimani died in a US airstrike ordered by Trump.

Today the US said 17 of the 34 are still being treated.

The military said symptoms were not immediately reported after the strike and in some cases became known days later.

Qassem Soleimani was killed in the rocket strike earlier this month

After the first reports that some soldiers had been hurt, Mr Trump referred to them as "headaches" and said the cases were not as serious as injuries involving the loss of limbs.

Last week the US military said 11 troops had been treated for concussion symptoms after the attack on the Ain al-Asad air base in western Iraq and this week said additional troops had been moved out of Iraq for potential injuries.

Pentagon spokesman Jonathan Hoffman told reporters that eight service members who had been previously transported to Germany had been moved to the United States.

Donald Trump ordered a US drone killed prominent Iranian commander Qassem Soleimani on January 3 in Iraq

Hoffman said the service members were transported earlier Friday and would receive treatment at either Walter Reed military hospital or their home bases.

Nine service members remain in Germany and are undergoing evaluations and treatment.

On Wednesday, Trump appeared to play down the injuries, saying he "heard that they had headaches and a couple of other things."

Pentagon officials have said there had been no effort to minimize or delay information on concussive injuries, but its handling of the injuries following Tehran's attack has renewed questions over the U.S. military's policy regarding how it deals with suspected brain injuries.