The prices of prepaid Australia Post packages have been raised by up to 30 per cent to take advantage of the online shopping boom.

For the first time, most of Australia Post's revenue comes from parcels instead of letters, and 70 per cent of parcels are from online transactions.

Higher costs: The price of prepaid packages have risen. Credit:Glenn Hunt

The rises, which come into effect on Monday, also mean the cost of getting a signature on delivery, a requirement for most online sellers, almost triples from $1 to $2.95.

Online retailers say the changes are a ''direct hit'' on their businesses and they have no option but to charge customers more.