Is that job posting really genuine?

In recent weeks, job-hunters have been receiving emails from - apparently - convenience food group Greencore, alerting them to job vacancies at the firm. In other cases, people have been approached by 'recruitment consultants' offering to match them with jobs at the company for a fee.

Unfortunately, as Greencore has now been forced to point out, it's all a scam. The company uses a small number of agencies for its recruitment, none of which would dream of asking job-seekers for cash. However, a number of people have been taken in by the fraud, and handed over the money.

As online recruitment websites have boomed, so too have the opportunities for scammers to make a quick buck from people desperate for a job. According to Crimestoppers, thousands of people are affected every year, with the average victim losing £4,000.

Victims can be any age, but fraudsters tend to particularly target 18-to-24-year-olds, as they're most likely to look for a job online.

Some victims have even turned up to a firm expecting to start their new job – only to find out that the employer has never heard of them.

"In 2008 around 150 people were coming to us each month for advice; that's now soared to 70,000. Last year we helped around 850,000 people and prevented £200,000-worth of jobs scams," says Keith Rosser, chair of Saferjobs, which launched in 2008 with the Metropolitan Police to help tackle the problem.

"Online scams, specifically regarding jobs, are becoming ever more intricate as fraudsters seek new ways to fool their victims. Many now tailor their scam to their victim, researching their career background online before targeting them with a convincing lie."

So what are the most common scams?

Advance-fee fraud
Here, scammers ask for money up front to pay for professional CV-writing, or for security and police checks. Sometimes, victims sign up for expensive training programmes, which either don't exist or give job-hunters fake qualifications. Often, the 'job' being offered is abroad, allowing scammers to ask for money up-front for visas, accommodation and the like.

Premium-rate phone scams
Job applicants are asked to call a premium rate number to find out more about how to apply - and then are kept on hold, racking up a big phone bill. In some cases, they're even fooled into going through a full interview on the phone for a fake job, which can take up to an hour and cost hundreds of pounds.

Work from home
'Earn £1,000 a week from home...' If it looks too good to be true, it probably is. These jobs may involve sending out letters or producing products, and offer big rewards. Unfortunately, the work often takes way longer than candidates are led to believe, and is often rejected on spurious grounds of poor quality. Other schemes ask you to pay for useless 'training materials'.

Money laundering
Be very wary of any job working at home doing 'financial processing': here, the odds are that criminals are looking to launder money. They will ask candidates to 'process payments' or 'transfer funds', and then use them to move dodgy cash around. People are often reassured by being given money up-front - but this payment can be cancelled before it's properly gone through; and victims may even be deemed guilty of fraud.

Reshipping fraud
Similarly, criminals often recruit victims for reshipping, or postal forwarding, scams, tasking them with repackaging stolen goods such as consumer electronics and forwarding them on. Workers are expected to pay the shipping charges themselves - but aren't reimbursed. Again, victims may be liable to criminal charges themselves.

Pyramid schemes
Often described as 'trading schemes' or 'network marketing', these scams recruit people to work from home, selling a product of some kind. However, the money is made by signing up new recruits; and when these schemes collapse, as they invariably do, those at the bottom of the pyramid are left with nothing.

Avoiding falling victim to a job scam is a question of damping down your optimism and scrutinising offers carefully. Poor spelling and grammar can often be a giveaway, as are webmail email addresses such as @Yahoo or @Hotmail.

Be very wary if you're asked to ring a premium rate number, or if you're directed to a different number, website or company name than the one you originally responded to.

And steer clear of anything where you're asked to put up money up-front, or where you're asked to sign up new members.