Senator Ed Markey, D-Mass., wants Jeff Bezos to take action against "coronavirus-inspired price gouging" on Amazon.

In a letter sent to the Amazon CEO on Wednesday, Markey asked Bezos to provide more information about what steps Amazon is taking to crack down on price gouging and how it determines whether an item is unfairly priced.

The letter comes after CNBC previously reported Amazon, Walmart and other e-commerce companies have struggled to curb third-party sellers who are overcharging for products that have spiked in demand amid the spread of the coronavirus.

Sellers inflated prices for hazmat suits, face masks and hand sanitizer, among other products. For example, before Amazon ran out of stock, N95 face masks were priced at $13.28, but CNBC found examples of face masks being sold for as much as $195.

"Although Amazon and the other sellers on Amazon.com have a right to expect a reasonable return on the products they sell, they do not have a right to impose unjustifiably high prices on consumers who are seeking to protect themselves against the coronavirus," the letter says. "But according to press reports, that is precisely what is happening."

Markey included a list of questions for Bezos seeking more information on Amazon's efforts to prevent price gouging, with a deadline for Amazon to respond by March 18. Among the questions asked were how Amazon tracks coronavirus-related price gouging on its platform, how many price-gouging warnings Amazon has issued to third-party sellers, how many listings Amazon has removed or suspended and what steps Amazon is taking to prevent price gouging. The letter also asks Amazon to clarify "at what level is an item unfairly priced."

An Amazon spokesperson told CNBC in a statement: "We agree with Senator Markey—there is no place for price gouging on Amazon and that's why our teams are monitoring our store 24/7 and have already removed tens of thousands of offers for attempted price gouging. We are disappointed that bad actors are attempting to take advantage of this global health crisis and, in addition to removing these offers, we are terminating accounts."

Last week, Amazon said it removed tens of thousands of deals from sellers that it accused of charging customers unfair prices. The company also blocked or removed more than 1 million products that made suspect or misleading claims about the coronavirus.