Hundreds of poultry farmers across Europe with millions of egg-laying hens are expected to flout a ban on conventional battery cages next year.

The new regulations are designed to eradicate the practice and dramatically enhance animal welfare.

According to European commission figures, 10 countries – including the UK – are set to be fully compliant with the new legislation by the time it comes into effect on 1 January 2012. Thus consumers can be sure that eggs from those member states have been produced in relatively high welfare conditions.

But eight countries – including Portugal, Belgium and Poland – are not predicted to make the grade, with more than 17 million hens expected to remain in old-fashioned battery cages by January.

And, while there were no new figures for five other member states including Italy, Greece and Hungary, campaigners say that those countries are unlikely to make the change in the next four months. As of last month, Italy alone had nearly 28 million hens still in so-called "non-enriched" cages.

The ban has been in the pipeline for 12 years, ever since the EU hens directive stated in 1999 that conventional non-enriched cages – in which birds do not have enough room to forage or stretch their wings – should be replaced by non-cage systems or "enriched" cages with more space, litter and perches.

Along with the EU's bans on veal crates and sow stalls – due to come into effect in 2013 – it is considered one of the most significant pieces of animal welfare legislation ever passed.

Peter Stevenson, chief policy adviser of Compassion in World Farming (CIWF), said he was "deeply disappointed" by the resistance of some EU countries. "I think what we've seen is that for some years the egg industry in many countries somehow believed that the 2012 date would be postponed.

"As they've now been repeatedly told by all three key EU institutions … that it's not going to be postponed, they're scrambling along to make up for lost time, and some of them are behind time."

For those countries planning to have abolished non-enriched cages by January, the failure of others to keep pace is infuriating.

Some nations, including Germany, have already imposed their own domestic bans. Others, such as Britain and the Netherlands, are expected to have made the full switchover by January.

But this has not come without a hefty cost to egg producers, some of whom have been pushed out of business.

Kelly Watson of the National Farmers' Union said egg farmers had spent about £400m on equipment in recent years, at a cost of £25 per bird.

Having invested that money, she added, farmers were concerned that their eggs would be undercut by imports from countries still using battery cages.

Duncan Priestner, who co-runs a medium-sized poultry farm with 120,000 hens in south Manchester, said he had spent more than £2m to reach the new standards.

He wants to see guarantees that imported, illegally produced eggs will not distort the UK market.

"What we don't want to see is these eggs coming into the country undermining our market," he said. "With this massive debt that we've got, we need every penny we can get back from the supply chain."

The NFU wants Brussels to impose an intra-community trade ban on the sale of eggs from non-enriched battery cages anywhere other than the member state in which they were produced. That way, it argues, there will no chance of the eggs being sold in Britain.

But Stevenson believes confusion in the aftermath of the ban will be short-lived and said such a move was unnecessary. "We don't need to propose a trade ban – we simply need the UK authorities to commit themselves to say 'we really are going to police eggs coming in'," he said.

One improvement that did meet with his approval was better food labelling to make clear the origins of egg ingredients, as championed by Jane Howorth of the British Hen Welfare Trust, a small charity that rehomes commercial laying hens.

Howorth said the biggest worry was not shell eggs bought by consumers in packs but liquid egg, used in processed food such as cakes and quiches. A third of the liquid egg used in the UK is imported.

"It's vital because we as consumers have made a really strong choice to purchase products with higher welfare [standards]," she said.

"To then go and buy a processed food product and have no idea whether the egg ingredient within that product comes from caged hens in Poland or wherever is wrong, in my view."

In a written statement, the European commission said it was up to member states to ensure that eggs not produced according to the new standards were not legally marketable.

But it said it was working to ensure that all countries took steps to implement the ban by January "to avoid distortions of the internal market".

A spokesman for the Department for Environment Food and Rural Affairs said: "The UK poultry industry has worked hard and made a significant investment to improve laying hen welfare, which would be undermined if producers in other countries don't also make the changes.

"We are pressing the European commission to take action to ensure compliance with the 2012 deadline and will keep this pressure up."