A war cemetery in west London dedicated to Anzac soldiers who died in World War I has been targeted by vandals for the second time this year.

Jane Palmer, a local councillor, discovered a series of grave stones at St Mary's Churchyard Cemetery in Harefield, around 20 miles west of central London, covered in blue spray paint on Sunday morning (local time).

She said she was brought to tears by the incident.

"In tears this morning at this desecration of Harefield Anzac War Graves," she tweeted.

Vandals also ripped up and threw pavers at some of the gravestones, causing them to chip, and tried unsuccessfully to saw the Australian flag pole in half.

It is believed the graves were vandalised overnight, and Metropolitan police are investigating the incident.

"Those who did this should give themselves up. This is not going to go away," said Rob Bryan, the neighbourhood inspector for Hillingdon North where the graves are located.

More than 100 Anzacs and one Australian nurse, treated at the nearby Harefield Hospital during WWI, are buried on the site.

About a quarter of the 112 Australian graves were vandalised.

Ms Palmer said the site linked the village with Australian history.

"The soldiers were cared for in Harefield Hospital at the top of the village and they were buried down in the churchyard that you see here," she said.

"The villagers have grown up [with] this for a hundred years and we are very proud of the Anzac graves and our link to New Zealand and Australian soldiers that gave their lives.

"I can't come up with any logical reason why anybody would do this."

Churchyard attendant Rowena said it was both frustrating and devastating to see damage inflicted at the site.

"I normally organise the Anzac Day service, so to discover this is totally devastating," she said.

"When you think that these graves have been here for 100 years and twice this year they've been desecrated ... I just cannot believe that anybody would do this to these soldiers who gave up their lives to fight for their mother country."

Unclear whether vandalism linked to April attacks

It still uncertain whether there is any connection between the grave stone vandalism and the attacks on the same cemetery on Anzac day earlier this year.

According to locals, the colour of the spray paint used to deface the grave stones is the same as that used in April.

There are no clear words or symbols in the graffiti that may indicate any motive or involvement from a particular group.

Mike Bullen, the assistant director for the Commonwealth War Graves Commission (CWGC), which is responsible for looking after the graves, said: "We are extremely disappointed by this deliberate act of vandalism and deplore the actions of those responsible."

"We have a team at the cemetery now, taking action to clean the headstones, and we hope to get the war graves back to their original condition," he said.

Mr Bullen said the CWGC were in contact with both the Australian and New Zealand High Commissions regarding the incident.