* Police execute search warrants in Australian coastal towns
* Australian media say one home belongs to suspect's sister
* Australian govt to be briefed by intelligence agencies (Adds details of search and government security briefing)
SYDNEY/WELLINGTON, March 18 (Reuters) - Australian police have searched two homes in towns on the New South Wales (NSW) mid-north coast linked to the investigation into Friday's mass shootings at mosques in the New Zealand city of Christchurch.
Police said that a search warrant was executed on Monday morning by the state's Joint Counter Terrorism Team (JCTT) at a home in the town of Sandy Beach, near Coffs Harbour, and shortly after another warrant was executed at a home in Lawrence, near Maclean.
The Australian Federal Police (AFP) and NSW Police declined to identify the owners of the homes.
"The primary aim of the activity is to formally obtain material that may assist New Zealand Police in their ongoing investigation," the agencies said in a joint statement.
They said the family of the Australian man arrested in Christchurch over the shootings were assisting police.
Australian media said one of the homes belonged to the sister of suspected white supremacist Brenton Tarrant, who was charged in New Zealand with murder on Saturday. who formerly lived in Grafton in the same region where the police searches took place, has been remanded without a plea and is due back in court on April 5 where police said he was likely to face more charges. Zealand, a country that has traditionally had very low homicide rates, has been placed on its highest security threat level after its worst peacetime mass killing. Fifty people were killed and dozens wounded in the attack at two mosques. ASSESSES THREAT
Australia is currently assessing risk posed by right-wing extremism and Australian Prime Minister Scott Morrison will on Monday chair a meeting of the national security committee, a source familiar with the matter told Reuters.
Morrison will be briefed by Duncan Lewis, head of the Australian Security Intelligence Organisation, and AFP Commissioner Andrew Colvin on the local response to the mass shooting, the source said.
The likelihood of an Australian terror attack remains at "probable", the midpoint of a five-level terror threat ranking that was introduced in 2015.