Every member state has ratified a UN convention banning the worst forms of child labour, the UN announced on Tuesday, in a historic first – though eliminating such practices remains distant.

The Pacific island nation of Tonga formally lodged its ratification with the International Labour Organisation (ILO) on Tuesday, meaning all 187 ILO member states have done so – the first convention ever to be universally ratified in the UN agency’s 100-year history.

ILO director-general Guy Ryder said: “Universal ratification of Convention 182 is a historic first that means that all children now have legal protection against the worst forms of child labour.

“It reflects a global commitment that the worst forms of child labour, such as slavery, sexual exploitation, the use of children in armed conflict or other illicit or hazardous work that compromises children’s health, morals or psychological well-being, have no place in our society.”

However, he was under no illusions that ratification equated to implementation.

The ILO estimates that there are 152 million youngsters under the age of 18 around the world in child labour, with around half in the worst forms, and 73 million doing work considered as hazardous.

Some 70 per cent of all child labour takes place in agriculture – two-thirds of which is unpaid family work – and is mostly poverty-related.

Nearly one in five African youngsters are in child labour.

Ryder told a press conference: “We still have a massive challenge ahead of us.

“The point here is that when a country takes on legal obligations to act in a certain way, that gives us real leverage to make progress.

“These things really do make an enormous difference but they’re not the magic bullet – and nobody would pretend they are.”

The convention was unanimously adopted in 1999 but has now been unanimously ratified.

It calls for the prohibition and elimination of child slavery, forced labour and trafficking and bans the use of children in warfare, prostitution, pornography, illegal activities such as drug trafficking, and in hazardous work.

The ILO said the incidence of child labour and its worst forms dropped by almost 40 per cent between 2000 and 2016, as ratification spread.

The sustainable development goals adopted by all UN member states in 2015 call for the end of child labour in all forms by 2025.

However, progress has slowed in recent years, particularly for children aged five to 11, and in some geographical areas.

And the Covid-19 pandemic is threatening to reverse progress and result in an increase in child labour for the first time in 20 years.

The pandemic has already wiped out the equivalent of more than 400 million jobs, and as vulnerability grows, families are looking for ways to supplement their incomes to survive.

Ryder said: “The temptation of children being pushed into the market for child labour is correspondingly increased – and there is evidence that this is happening.”