Airmiles collectors face losing all their points if they are not currently adding to the account.

The operators of the loyalty scheme are sending out letters to 1.7 million customers who have not collected any points in the last two years, warning them their account will be closed and all points lost unless they add at least one more mile over the next six months.

According to the British Airways-owned scheme, the decision is allowed under the terms and conditions.

Andrea Burchett, director of relationship marketing and insight for Airmiles, said: “Thousands of members have positively responded to their letters and have gone on to collect Airmiles again with our partners Lloyds TSB, Shell, Tesco and shopping online.

“Many members are thanking us for making contact with letters and reminding them of their balance or advising them of partners to collect with.”

A spokesperson from Which? Holiday said: “It is key that customers know about the new policy and shop around when collecting points. People have to be aware of these policies and take action as soon as possible to make sure they don’t lose out.

“There are alternative ways of accruing points other than flying. It is in the best interests of customers to go online and find out about those other ways.”

Airmiles said those who do not collect the minimum one mile in the next six months will keep their account, but any collected points will expire.

Most loyalty schemes have a time limit on points, Airmiles added.

Airmiles have predicted a ‘loyalty boom’ in 2009 as consumers look for ways to make their money stretch further.