Westpac has refunded A$20 million to around 820,000 customers after it accepted a customer complaint that it had not clearly disclosed the types of credit card transactions that attract foreign transaction fees.The Australian Securities and Investment Commission said Westpac had notified it that customers may have been incorrectly charged foreign transaction fees for Australia dollar transactions processed by overseas merchants.Westpac's terms and conditions did not clearly state that foreign transaction fees would be charged for such transactions.Westpac has since updated its disclosure to make it clear that Australian dollar transactions processed by overseas merchants attract a foreign transaction fee.ASIC also issued a warning to consumers about foreign transaction fees, which it said were not always adequately disclosed."It may come as a surprise to consumers that transactions made in Australian dollars with overseas merchants, or processed by a business outside Australia, can attract a foreign transaction fee," ASIC said."This can even occur where the merchant's website has an Australian address or where a foreign business advertises and invoices prices in Australian dollars. It may not always be clear that the merchant or entity is outside Australia."ASIC said credit issuers needed to ensure that the disclosure of such fees is clear. It recommended that consumers who make frequent purchases from overseas merchants look for cards that do not charge foreign transaction fees."Foreign transaction fees include fees on purchases that are converted from a foreign currency to Australian dollars, that are made in Australian dollars with merchants and financial institutions overseas, or are made in Australian dollars and are processed outside Australia.