San Francisco, Dec 8 : Amazon has announced that it's testing a new subscription model for unlimited grocery delivery for Prime members in three cities of the US. For an additional monthly charge of $9.99, Prime members in Denver, Sacramento and Columbus can get unlimited delivery on Amazon Fresh and Whole Foods orders over $35, reports The Verge. Those who subscribe to this plan will also receive unlimited 30-minute pick-up on orders of any size. "We're always experimenting with features to make shopping easier, faster, and more affordable, and we look forward to hearing how members who take advantage of this offer respond," Tony Hoggett, Amazon's senior vice president of worldwide grocery stores, was quoted as saying. Prime members presently pay $6.95 for Fresh orders between $50 and $100, and $9.95 for items under $50. However, Prime members were not always required to pay for Fresh delivery on orders over $35. Amazon began charging delivery costs for Fresh grocery orders under $150 in January, removing a benefit that allowed Prime members free delivery on orders over $35. Amazon then reversed its decision in October, lowering the free grocery delivery threshold from $150 to $100. In September, Amazon announced that it will introduce 'limited advertisements' to its Prime Video streaming service in 2024 as it aims to put more cash into creating TV shows and films. In addition, the company said it will roll out the "ad-free" subscription tier for an extra $2.99 per month for Prime members in the US -- a similar move which was taken by competitors such as Disney+ and Netflix. /IANS