Iraq will close its border with Jordan on Wednesday due to anti-government protests that have blocked the main highway linking the two countries, a military official said.

"We received orders from the defence ministry to close the border because of demonstrations that continue to block the motorway," the official said on Tuesday.

Jordan's official news agency Petra said the Iraqi authorities had informed the kingdom that they would close the Trebil border post starting from Wednesday at 6:00 am (0300 GMT) for "their own private reasons."

It did not say when the border would reopen.

The Trebil crossing is the only checkpoint linking Iraq and Jordan, and lies on a key trade route.

Protests by Sunni Muslims against Shiite President Nuri al-Maliki in Anbar province in western Iraq have blocked the road, which leads to Amman and to neighbouring Syria.

Iraq's protesters call for the release of prisoners they say are detained because of their Sunni background, and an end to the alleged misuse of anti-terror legislation by the Shiite-led authorities against their community.