US Secretary of State John Kerry has announced that the United States is ready to receive as many as 100,000 refugees, many from Syria, sparking fears among lawmakers that this would increase the chances of Muslim terrorists masquerading as refugees to enter the US and launch attacks.

"Now the Obama administration wants to bring in [more] Syrians without a concrete and foolproof plan to ensure that terrorists won't be able to enter the country... this isn't good," said US Sen. Chuck Grassley, R-Iowa, and US Rep. Bob Goodlatte, R-Virginia.

A statement from the lawmakers, who head the congressional judiciary committees has likewise expressed doubt on the administration's "trust me" attitude, ABC News said.

Saying it is in keeping with the best tradition of America as a land of second chances and a beacon of hope, Kerry said the United States will be increasing the number of migrants it will accept next year until 2017 with priority given to Syrian refugees displaced by war.

Kerry made the announcement in Berlin on Sunday following his meeting with German Foreign Minister Frank-Walter Steinmeier, according to ABC News.

Kerry said the new plan limits the annual refugee US visas to 85,000 in 2016, up from the current 70,000, adding that the figure could reach up to 100,000 in 2017.

"This step that I am announcing today, I believe, is in keeping with the best tradition of America as a land of second chances and a beacon of hope,'' he told a media conference, said the New York Times.

"This will be accompanied by additional financial contributions for the relief effort,'' Kerry added.

Aside from Syrian refugees, those from strife-torn areas of Africa would also be prioritised. The Syrians who would be taken in next year would come from a United Nations list of about 18,000 refugees, said Kerry.

Around 250,000 people have died and 12 million have fled their homes in the past four years as a result of the ongoing war in Syria. The US has since taken in only about 1,500 Syrian refugees, which was way below the targeted number for 2016 and 2017, and way too small compared to the hundreds of thousands that Germany had and will continue to accept.

CNN said Germany remains to be the most desirable destination for most of the migrants.

Kerry said the US is only doing what it can manage immediately, and that it cannot take shortcuts on security checks.

Last year, refugees from Iraq, Somalia and Bhutan were the three largest groups admitted in the US, NYT said. Syrians were reportedly at the bottom of the list of nationalities.