U.S. tempers part of Trump travel ban amid big protests, criticism

* Republicans Corker, McCain, Graham criticize directive

* Washington, New York, Los Angeles among cities with protests

* Trump defends directive, says it is "not about religion"

By Doina Chiacu and Steve Holland

WASHINGTON, Jan 29 (Reuters) - President Donald Trump's administration on Sunday tempered a key element of his move to ban entry of refugees and people from seven Muslim-majority countries in the face of mounting criticism even from some prominent Republicans and protests that drew tens of thousands in major American cities.

Trump signed the directive on Friday, but the policy appeared to be evolving on the fly. Democrats and a growing number of Republicans assailed the move and foreign leaders condemned it amid court challenges and tumult at U.S. airports.

The president's critics have said his action unfairly singled out Muslims, violated U.S. law and the Constitution and defiled America's historic reputation as hospitable to immigrants.

In a fresh defense of the action on Sunday, Trump said his directive was "not about religion" but keeping America safe.

Trump has presented the policy as a way to protect the country from the threat of Islamist militants.

U.S. Homeland Security Secretary John Kelly said in a statement that people from the seven countries who hold so-called green cards as lawful permanent U.S. residents would not be blocked from returning to the United States from overseas, as some had been after the directive.

All green card holders who were detained at U.S. airports had been admitted into the country by late Sunday, a U.S. official familiar with the process told Reuters. The source could not provide a figure of how many people whose re-entry had been delayed, in some cases for hours.

Outside the White House, where some viewing stands from Trump's Jan. 20 inaugural parade still stood, several thousand protesters denounced him, carrying signs such as "Deport Trump" and "Fear is a terrible thing for a nation's soul."

Protests also were staged in cities and airports in New York, Los Angeles, Boston, Houston, Dallas and elsewhere.

The Republican president on Friday put a four-month hold on allowing refugees into the country, an indefinite ban on refugees from Syria and a three-month bar on citizens from Iran, Iraq, Libya, Somalia, Sudan, Syria and Yemen.

Border and customs officials struggled to put Trump's directive into practice. Confusion persisted over details of implementation, in particular for the people who hold green cards.

Senator Bob Corker, the Republican chairman of the U.S. Senate Foreign Relations Committee and a Trump supporter, said the president's order had been poorly implemented, particularly for green card holders.