British people who vandalise war memorials could face 10 years in prison and an unlimited fine, under a new law being debated by MPs in London.

The war memorials Bill, initially introduced as a private initiative of a group of backbench MPs, has now been taken up by both the British government and the chief opposition party, with leading ministers praising its purpose.

But although the measure to stiffen penalties for those who deface or vandalise such memorials appears to enjoy broad public support, critics argue that no new law is actually required, and that judges will not find it easy to agree on a definition of what constitutes a war memorial.

The attack on Britain's public monuments started two weeks ago, when anti-racism protesters in the western English city of Bristol tore down a statue of Edward Colston, a 17th-century slave trader, and dumped it into a nearby harbour.

Subsequently, the monument to Britain's greatest war-time leader Winston Churchill, erected opposite Big Ben in London, was covered in graffiti that claimed Churchill was a racist.

And in a move which prompted even greater outrage, a protester attempted to set the United Kingdom's national flag on fire by climbing on the Cenotaph, the memorial to the country's war dead, which has stood just outside the British prime minister's residence in Downing Street for a century.

Prime Minister Boris Johnson blasted these attacks as "absurd and shameful", saying that the UK "cannot lie about its history".

Meanwhile, Mr Sadiq Khan, London's Mayor, was accused of surrendering the capital's streets "to the mob" after he ordered the boarding-up of key monuments in central London, including the Cenotaph, which is a regular point for many tributes and parades by war veterans and their successors.

The Desecration of War Memorials Bill was introduced this week in Parliament by Mr Jonathan Gullis and Colonel James Sunderland, two backbench MPs who entered Parliament at last December's general elections. Both belong to the ruling Conservative Party, and they swiftly got the backing of a further 125 government legislators.

Mr Gullis told MPs: "Let us not forget the sacrifice and bravery of those who paid the ultimate price."

"Young men and women who gave up their futures, their loves, their lives and their dreams" did not do it so future generations would "sit idly by as monuments dedicated to their eternal memory are desecrated", he added.

If the law is passed, people convicted of vandalising monuments can be punished with up to 10 years in jail, unlimited fines, or both.

Usually, Bills introduced by individual MPs get nowhere, as the government, which controls the parliamentary agenda, provides no time to debate them. Not on this occasion, however, for the Bill got the broad backing of Home Secretary Priti Patel and Mrs Suella Braverman, the Attorney-General.

More unusually still, Labour, Britain's chief opposition party, also signified its backing; its shadow home secretary Nick Thomas-Symonds said the party would support a change in the law to make damaging war memorials a specific offence.

Under existing legislation, vandalism can already be punished with up to a decade behind bars, if the cost of the damage caused is more than £5,000 (S$ 8,700).

Judges can also consider damage caused to "heritage" or "cultural assets" as aggravating factors during sentencing.

The only difference is that under current conditions people charged with causing damages worth less than £5,000 are sent to hearings in the lower magistrates court where the penalties are far lighter, so the theoretical top penalty is almost never applied.

If the new legislation is passed, however, penalties for vandalising monuments can be uniformly stiff, regardless of the value of damage caused. "We are enabling our judiciary to use their discretion," said Mr Gullis, the MP.

However, critics doubt that new legislation is required to cover such a small procedural difference. And they point out that, even if the new law is adopted, defining what one means by war memorials will not be easy.

Strictly speaking, Churchill's statue is not a war memorial, so some of the examples of vandalism which infuriated British legislators and politicians over the past few weeks will not be affected by the new legislation.

Still, the initiative answers feelings of serious discontent in the ranks of the ruling Conservative Party membership.

In a recent opinion poll, 85 per cent of Conservative voters expressed stiff opposition to the removal or the defacing of statues, even if those are of highly controversial figures.

And among the broader electorate, opinions remain sharply divided, with about 40 per cent supporting the removal of statues of previous slave traders, while around 35 per cent oppose the move.

On Churchill, however, there is little doubt: Only a fifth of those asked in a recent opinion poll supported any questioning of his statue in central London.