(Bloomberg) -- U.S. aviation regulators are seeking a$350,000 fine against Amazon.comInc., the Seattle-based online retailer, for allegedlysending hazardous shipments as air cargo.

E-commerce giant Amazon, which has made two deals this year inan attempt to create its own air-shipping network, was chargedMonday with improperly sending a caustic chemical that leaked andcame in contact with nine workers at a United Parcel Service Inc.facility, the Federal AviationAdministration said in a press release.

“Amazon has a history of violating the hazardous materialsregulations,” the FAA said in the release. “From February 2013 toSeptember 2015 alone, Amazon was found to have violated thehazardous materials regulations 24 other times.”

The shipment of corrosive drain cleaner wasn’t properlypackaged, declared and labeled, the FAA said in the release. Amazonalso failed to include emergency response information on thepackage and didn’t train employees on handling hazardousmaterials.

Assembling fleet

Companies hit by FAA fines can negotiate with the agency andpenalties are sometimes reduced. Amazon spokesman Craig Bermandidn’t immediately respond to an e-mailed request for comment.

The FAA’s action comes a month after Amazon agreed to take asmuch as a 30% stake in Atlas Air Worldwide Holdings Inc. As part of the deal,Atlas will acquire and operate 20 Boeing Co. 767-300 freighters forAmazon, according to a May 5 statement.

In March, Amazon announced it would work with Air TransportServices Group Inc. to operate another 20 Boeing 767freighters.

The retailer is moving swiftly to build up its delivery systemin an attempt to reduce its dependence on UPS and FedEx Corp. as itexpands its Prime membership service that delivers some orders inas little as one day.

Global network

Chief Financial Officer Brian Olsavsky downplayed Amazon’sambitions in an earnings call in January, saying the company wantsto supplement the two shippers, not replace them. Documentsreviewed by Bloomberg News reveal the company may be planning abolder strategy to create a global delivery network to control theflow of goods from factories to customers’ doorsteps.

At the same time, Amazon is developing drones capable ofshort-distance, rapid deliveries of small items. The company hasreceived FAA permission to test unmanned aircraft and is also doingdevelopment in other nations.

The FAA didn’t detail Amazon’s previous violations in Monday’spress release. According to previous press releases on its website,the FAA has opened enforcement actions against Amazonfor shipping flammable paint and other items without properpackaging and marking in at least four previous cases since 2014.The agency sought a total of $314,000 in fines in those cases.

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