When screening was introduced two years ago by the former funding body ELWa, it identified "a huge need", says John Graystone, chief executive of the colleges' body fforwm.
"I'm hearing figures of around 50 to 60 per cent across the board - far greater than many of us realised," he said. "You can't ignore it. Yet we haven't the funding to respond. If there aren't any resources, we need to redirect these from core budgets."
In last year's skills action plan, the Assembly government revealed that 24 per cent of the working-age population lacked level 1 literacy skills and 53 per cent level 1 numeracy. In Wales, 20 per cent have no qualifications compared with 14 per cent across the UK.
At Pembrokeshire College, 60 per cent of new students need help, including some with GCSEs, says principal Glyn Jones. But European Social Fund (ESF) money that supported screening runs out this year.
Pembrokeshire and other colleges are at the sharp end of education minister Jane Davidson's call to drive up basic skills. Mr Jones must now review his curriculum and annual plan to ensure screening carries on. "This might be at the cost of cutting back on business support and some community activities," he said.
Barry Walters, assistant principal, says identifying learners at risk via screening is critical. "It's a very important part of the retention strategy. If you leave it six weeks into the course, it's too late - but that's how we operated in the past," he said.
"Since 2003-4 we've made rapid progress. We can't afford not to do this.
But we shouldn't have to seek alternative funding for it to be supported.
It will cost around pound;150,000 to staff the learning support required for 20067."
At Pembrokeshire, which has six basic skills teachers, screening is done online. "Having young people come in and take paper tests raises the question of marking - it's hugely labour intensive," said Mr Walters. "When we appointed an IT manager, one of the first tasks we gave him was to produce something that would identify where support was needed from day one."
The statistics show the urgency. "We screened 282 entry level and level 1 learners in 2004-5, of which 190 required support with literacy and 198 with numeracy," said Mr Walters. "In 2005-6, of 317, 204 required literacy support and 240 numeracy help.
"These are staggering figures, though I understand in line with the national average. The ESF money was hugely important. Attainment at college increased from 61 per cent in 2003-4 to 76 per cent in 2004-5, so identifying the needs of learners at the start is very important."
As FE wrestles to meet needs with frozen budgets and with basic skill tutors in short supply, Mr Graystone wants a more co-ordinated approach between colleges and schools.
"They should be working together at a younger age. There should be a record of these people when they are coming up," he said.