Getting an internship or a holiday job while at university makes students three times more likely to get a well-paid job on graduating, a survey found.

Among final-year undergraduates, 36 per cent who had work experience with a leading employer while at university received at least one offer of a graduate-level post. The figure dropped to 11 per cent among third or fourth-year students with no careers-related work experience.

The findings, based on interviews with 18,252 undergraduates at 30 leading universities, illustrate why students are prepared to work for little or no pay in internships. Four out of five students said they had done careers-related work experience, with an average duration of six months or the equivalent of two long summer holidays.

These included some undergraduates on sandwich courses that included a placement in industry for 13 months. Others said that they worked during a gap year or had part-time work in term time.

Martin Birchall, managing director of High Fliers Research, which conducted the survey, said: “Our research highlights that work experience is an essential part of preparing for the graduate job market.”

“Students who just focus on their degree studies without spending time in the workplace are unlikely to develop the skills and interests that graduate employers are looking for.”

Securing a high-level job is becoming more competitive, with final-year students in the “class of 2013” making more than seven applications each to graduate employers, a total of 427,000. This time last year, there were 360,000 applications.

More than two thirds of students said they began job-hunting in their second year or earlier, and 41 per cent had sent off their applications by October, within a month of starting their final year.

The average expected starting salary for new graduates rose slightly to £22,800, up by £200 on last year.

Students at the London School of Economics had the highest expectations for starting salaries, averaging £28,700, but with 43 per cent expecting to earn above £30,000, followed by undergraduates at Oxford (£26,500), Imperial College London (£26,400), Warwick (£26,300) and Cambridge (£26,200).

Marketing remained the most popular career choice, as last year, followed by the media, consultancy and teaching.

Investment banking was the seventh most popular career, lower than working for a charity and research.

A high proportion — 26 per cent — opted to remain in higher education for postgraduate study, usually a master’s degree, which many students believe will give them an edge in the jobs market over graduates with only a first degree.

Just 11 per cent said they would take time out after graduating to go travelling, the lowest level recorded by the annual graduate careers survey.