Philippines: 10 soldiers killed in 'friendly fire'

The Philippine army has been bombing parts of Marawi City occupied by fighters [Romeo Ranoco/Reuters]

Ten Philippines soldiers were killed by "friendly" fire in a military air raid during efforts to take back a southern city sieged by fighters, the defence minister said on Thursday.

Seven other soldiers were wounded on Wednesday when two air force SF-260 close air support planes dropped bombs on a target in the heart of Marawi City, Delfin Lorenzana told reporters. The first plane hit the target but the second missed.

"It's very sad to be hitting our own troops," Lorenzana said. "There must be a mistake somewhere, either someone directing from the ground, or the pilot."

The Philippine armed forces have been using a combination of ground operations by soldiers and helicopters air raids to try to dislodge Maute rebels linked to the Islamic State of Iraq and the Levant (ISIL) group, who have occupied parts of Marawi City for eight days.

The Maute group has proven to be a fierce enemy, clinging on to the heart of Marawi City through days of air strikes the military has said are "surgical" and on known rebel targets.

The deaths of the soldiers takes the number of security forces killed to 38, with 19 civilians and 120 rebel fighters killed in the battles in Marawi over the past nine days.

Tens of thousands of people have fled the fighting.

Lorenzana, the minister, said fighters who were Saudi, Malaysian, Indonesian, Yemeni and Chechen were among eight foreigners killed fighting with the Maute rebels.

In an earlier text message to reporters, he said of the "friendly fire" incident: "Sometimes that happens.

Sometimes the fog of war ... The coordination was not properly done so we hit our own people."

Thousands of civilians have fled the fighting in Marawi City [Romeo Ranoco/Reuters]

'Relentless air strikes'

Marawi, a mostly Muslim-populated city of 200,000 people, lies about 800km south of the capital, Manila.

President Rodrigo Duterte declared martial law in the south throughout mid-July after the fighters went on a deadly rampage in Marawi last week, following an unsuccessful military raid to capture Ismilon Hapilon - a veteran Filipino fighter regarded as the local ISIL leader.

"Since the Philippine government announced martial law, there have been relentless air strikes, 'surgical air strikes,' as the Philippine military described it," Al Jazeera's Jamela Alindogan, reporting from the outskirts of Marawi City, said.

"There have been organisations and civilians here who have been asking the government to stop the air strikes, simply because of the danger they pose for civilians."

More than 2,000 people are estimated to be trapped in the conflict zones in Marawi, fearing for their lives amid violence by fighters and military air raids.