NEW YORK (Reuters) - U.S. airline and online booking agency shares slumped for the second consecutive day on Tuesday, and some industry executives have begun speaking out against the Trump administration’s ban on travel from seven majority Muslim nations.

An American Airlines airplane prepares to land at the Jose Marti International Airport in Havana September 19, 2015. REUTERS/Carlos Garcia Rawlins

Share prices of major U.S. airlines and third-party travel booking sites have plunged since Friday when President Donald Trump issued an order temporarily barring entry to the United States from nationals of seven Muslim-majority countries. Confusion over who was affected, and protests at some major airports, disrupted travel throughout the weekend.

American Airlines Group Inc AAL.O shares dropped 2.1 percent on Tuesday to $43.96. United Continental Holdings Inc UAL.N stock price slipped 2.89 percent to $69.65.

American Airlines Chief Executive Officer Doug Parker, in a memo sent to employees on Monday and posted on a company website, called the order “divisive” and said that it had caused “difficult operating conditions” for some employees.

“As a global employer, however, this Executive Order does not affect the values that this company is built upon — those of diversity, inclusiveness and tolerance,” Parker said in the memo.

Shares in Delta Air Lines Inc DAL.N declined for a second day on Tuesday and were down about 5 percent since Friday. Delta has declined to comment on the travel ban or the president's effort on Monday to pin blame for weekend travel delays on a computer outage that grounded some Delta flights on Sunday evening.

The company did issue a statement on Tuesday congratulating Elaine Chao, Trump’s nominee to run the Department of Transportation, on her confirmation.

Share prices of online travel agencies Expedia Inc EXPE.O and Priceline Group Inc PCLN.O also fell in afternoon trading.

Online travel booking agency Expedia, in a declaration filed with an official complaint from Washington state’s attorney general on Monday, said the travel order “jeopardizes its corporate mission and could have a detrimental impact on its business and employees, as well as the broader U.S. and global travel and tourism industry.

The number of entrants to the United States directly affected by the order is relatively small, Trump administration officials said on Tuesday. Since the order, 721 travelers with visas from the seven countries were denied boarding on U.S.-bound flights, acting Customs and Border Protection Commissioner Kevin McAleenan said at a briefing. The department has also processed 1,060 waivers for legal permanent residents, such as green card holders, officials said.

“The sense of uncertainty created by (the executive order)… just makes it a difficult time to think about traveling,” industry analyst Bob Mann of R.W. Mann and Co said.

Over the weekend, some airlines said they had to rework their flight attendant and pilot rosters, and thousands of demonstrators took to airports across the United States to protest the ban, clogging terminals and delaying travelers.