Susan Pember, director of the Adult Basic Skills Strategy Unit, said teachers should expect more of learners - even though many have not set foot inside a classroom for years.
More than a million "learning opportunities" are being provided for people with basic skills needs this year, compared with just 240,000 three years ago. Many are set up with the co-operation of employers who are seen as key players in raising overall skill levels.
But in spite of the fact that teachers are working with the most up-to-date materials, not all learners are given enough encouragement to realise their potential, Ms Pember said.
Teachers still had low expectations of such learners, she said. "They do not raise expectations or signpost them to move along to the next learning opportunity quickly enough."
The government, which originally pledged to help 750,000 adults improve basic skills by 2004, has now set a new target of helping 1.5 million people by 2007. Some seven million adults lack basic literacy or numeracy - about half of whom are in employment.
The new target means reaching more people who are reluctant to recognise they lack basic skills, let alone keen to return to learning. "This group of people have really bad baggage about their past in education," said Ms Pember.
Last month saw the launch of the first in a series of new specialist qualifications for teachers of adult basic skills. From this term, all adult basic skills teachers appointed by colleges are required to hold or be working towards a specialist qualification approved by the Further Education National Training Organisation, as well as be trained teachers.
Ms Pember's unit is working with large employers such as the armed services and the NHS so that employees can improve basic skills in colleges or the workplace.
Next year has been designated the "year of the employee" so that more workers are made aware of opportunities to improve basic skills. "We have to make employers sit up and see that it's their problem and that it's hitting the bottom line," said Ms Pember.