(Reuters) - United Parcel Service Inc UPS.N and FedEx Corp FDX.N said they resumed flights at Houston's main airport on Thursday afternoon and restarted some Texas operations crippled by Hurricane Harvey.

A United Parcel Service (UPS) logo is seen on a car in center of Warsaw January 16, 2013. REUTERS/Kacper Pempel

UPS UPS.N, the world's largest package delivery company, has restored service to more than 150 zip codes in Texas over the last 24 hours though operations remained at a standstill in storm-battered Houston and other Gulf Coast areas, UPS spokesman Matt O'Connor said. Trucks for both companies returned to deliveries on routes in Corpus Christi.

“The safety of our employees comes first and we will be resuming service as soon as it is safe to do so,” O’Connor said. “In Houston, that will come down to local areas that were impacted and how quickly water subsides.”

The first UPS plane into Houston’s George Bush Intercontinental Airport will land on Thursday afternoon and three flights were expected to depart Friday morning, O’Connor said. The airport was closed to commercial flight operations from Sunday and said limited flight operations were resuming Thursday afternoon.

Memphis-based FedEx was also running some ramp operations at Bush and resumed limited delivery service in parts of Corpus Christi and Victoria, Texas, a spokeswoman said.

As of Thursday, FedEx Express service remained suspended in lake Charles and 22 cities in Louisiana, and more than 240 cities in Texas including Galveston, according to a company spreadsheet tracking disruptions.

Harvey came ashore over the weekend as the most powerful hurricane to hit Texas in a half-century. Days of heavy rains and flooding of streets, highways, and rail networks forced UPS UPS.N and rival FedEx Corp FDX.N to shutter facilities and cease delivery to huge swaths of southeast Texas and Louisiana.

UPS halted operations in Austin, northwest of Houston, and Corpus Christi, along the coast, before Harvey made landfall, O’Connor said. As of Thursday, package sorting facilities and deliveries resumed in Austin and in some areas of Corpus Christi.

“Now that the weather is subsiding in communities in Corpus Christi, and our employees are able to come back home, we will continue to resume service as it is safe to do so,” O’Connor said.

Two days ago, the storm stopped or sharply limited deliveries to more than 730 zip codes in Texas and Louisiana, he said.