Some students work to pay for 'essentials' says the NUS

The University and College Union, which represents university lecturers, says working long hours makes them too tired to participate in college life.

This could impact on their CV when they face the job market, say lecturers.

The government argues more support has been given to reduce the time students have to work to boost their income.

Estimates say that half of all students who do a full-time degree, work to help pay their way. On average they work 14 hours a week, but some work more than 20 hours a week, says the BBC's Sarah Pennells.

Concern

Potentially, students who work the longest hours may be too tired to get the most from their lectures, but they could also be too busy to get involved in the student paper or join clubs and societies that could help their CV stand out.

Sally Hunt, from the University and College Union, said there was concern about the number of students who are working long hours.

"A student who's had simply to work to live will not necessarily have had the choices to build their career and it means they're at a detriment immediately they go into the job market," she said.

"Employers have to look for the relevant experience."

Research by the National Union of Students shows that 10% of students have considered dropping out of university because of financial concerns.

Ama Uzowuru, vice president of the NUS, says students are not working to buy gadgets such as MP3 players and DVDs, but the essentials such as books and food.

"They leave university and they haven't worked on the student newspaper and they haven't done those activities at university that they could do," she said.

'Work value'

Other experts believe that the experience of working can actually help students secure a job when they graduate. Fraser Lewis, of Graduate Recruitment Company, says employers value work experience, even if it is not directly relevant to their career.

The government rejects the charge that students are forced to make a choice between financing their university degree and getting a good CV.

Education Minister Bill Rammell says the government has put a new package of financial support in place for students starting university this autumn, which should mean students do not have to work more than they want to.

"We don't want students to work excessive hours, but as long as students don't work more than about 15 hours a week, I think there are some advantages," he said.