British police are reviewing security operations ahead of the centenary of the Anzac landings following a foiled alleged terror plot in Australia.

The annual Anzac Day ceremonies - commemorating Australian and New Zealand Army Corps' First World War battle in Gallipoli on April 25 - take on extra poignancy this year, marking the 100th year of the Turkish conflict.

Australians and New Zealanders in the UK traditionally observe the occasion by holding services in Westminster and at Hyde Park.

But concerns have been raised after five Australian teenagers were arrested on Saturday on suspicion of planning a terrorist attack on the Anzac Day celebrations in Melbourne.

"Following counter-terrorism arrests in Australia this weekend and allegations of attack planning against Anzac Day commemorations and police officers in Australia, we are reviewing security plans at related events in the UK," Metropolitan Police Deputy Assistant Commissioner Neil Basu said in a statement.

"We already have protective security plans in place for major Anzac events in the UK but as a sensible precaution all forces have been asked to review security arrangements at related events to ensure they are safe and secure for the public and officers.

"While there is no information to suggest a specific threat to related events in the UK - and the current UK threat level remains unchanged - the public should remain vigilant."

The Australian government raised the terror warning level in response to the domestic threat posed by supporters of the Islamic State group.

In September last year, the group's spokesman, Abu Mohammed al-Adnani, issued a message urging attacks abroad, specifically mentioning Australia.

Next week's commemorations are due to begin with a dawn service on Saturday at Wellington Arch, Hyde Park Corner, followed by a wreath-laying ceremony at the Cenotaph and a commemorative service at Westminster Abbey.

Victorian Premier Daniel Andrews says the systems in place to protect people from such attacks are working.

"Just how serious the threat that this plot posed in very real terms, not just to members of the Victorian police, but to the Victorian public."