That's it from the NSW Police and Superintendent Paul Dunstan.

For more coverage of this story head to the ABC News website.

That comment has prompted Palestine Action Group organiser Josh Lees to interject into the press conference.

"Mr Lees now is not the time or place Mr Lees," Superintendent Dunstan said.

 "Josh I will speak to you after this has occurred. I am not engaging in conversations with you now Mr Lees.

"It's not the time or the place."

Superintendent Dunstan said the actions of the group was "entirely out of character".

"We've been working with the Palestine Action Group (PAG) for the last two years," he said.

"We've been able to maintain a good relationship with that group over the past two years what happened today was entirely out of character.

"What happened today was so disappointing all the good will we've worked to with that group really has been damaged."

Superintendent Dunstan has been asked about his use of the phrase "set upon".

"A large group of approximately 50 to 100 people came marching in the direction of police, straight into our line, we were set upon," he said

"Two police were injured, one sustained a laceration to his nose, the second officer required paint in his eye which needed to be flushed out.".

Police have described the group as "very angry" in defending their use of force this morning.

"I must emphasise police did not go out with an intent to use force this morning," Superintendent Dunstan said.

"We were set upon by a pack of very angry protesters and we were required to use an amount of force commensurate with what was forced upon us." 

Superintendent Dunstan said officers will be monitoring protest activity until the expo wraps up.

"Police will maintain a strong presence in and around the ICC in the coming days while this event takes place at the ICC," he said.

Superintendent Dunstan said officers had paint thrown at them in the clashes this morning.

"The group continued to yell and threaten police and a further incident took place when paint, a bucket of paint, was picked up and thrown at police," he said

"Police were once again required to intervene and a number of people were arrested."

The press conference is now moving to the use of "OC spray", otherwise known as pepper spray, by police on protesters.

"During that incident a number of people were arrested and a number of tactical options including OC spray were used by police," Superintendent Dunstan said

"Police eventually got that group into the park when a further incident took place when the protesting group picked up some fencing and started to push it in the direction of police.

"Once again police were required to intervene and push the group back so the exclusion line could not be broken."

Superintendent Dunstan said officers were setting up an exclusion zone when they were "set upon" by protesters at the ICC this morning.

"Police were in the process of setting up an exclusion area in and around the conference where they were set upon by a large group of protesters that made their way inside an exclusion zone area," he said.

"During that incident a number of people were arrested and a number of tactical options including OC spray were used by police."

NSW Police Superintendent Paul Dunstan will update the media shortly after 13 people were arrested in clashes with officers outside a defence expo at the Sydney International Convention Centre.