A worker loads customer orders into a waiting tractor-trailer inside the million-square foot Amazon distribution warehouse that opened last fall in Fall River, MA on Mar. 23, 2017.

Amazon is telling third-party merchants it's "temporarily prioritizing" household staples, medical supplies and other product categories in response to a surge in demand from the coronavirus outbreak.

The change went into effect Tuesday and is expected to last until April 5, according to a document obtained by CNBC. It applies to third-party sellers and vendors, or retailers who sell directly to Amazon, who sell on Amazon's U.S. and EU marketplaces.

Third-party sellers on Amazon who sell products not related to coronavirus demand may start seeing delays when they try to send their items to an Amazon warehouse. Amazon said it will continue to ship out merchants' existing inventory in its warehouses, as well as any shipments created before March 17.

An Amazon spokesperson told CNBC it's seeing surges in online shopping, causing some products like household staples and medical supplies to go out of stock.

"With this in mind, we are temporarily prioritizing household staples, medical supplies and other high-demand products coming into our fulfillment centers so we can more quickly receive, restock and ship these products to customers," the spokesperson said. "We understand this is a change for our selling partners and appreciate their understanding as we temporarily prioritize these products for customers."

The company told sellers it's "working around the clock to ensure availability on these essential products," adding that it will notify them once it resumes regular operations.

On Saturday, Amazon said it was running out of stock of popular household items and that some of its "delivery promises are longer than usual." In-demand items such as toilet paper and bottled water showed that many listings were out of stock. Amazon's normally speedy one-day and two-day delivery options also showed delays of several days.