US mayors vow to fight Trump's deportation pledge

US officials said they hoped President-elect Donald Tump would back down from a vow he made to withhold funds from "sanctuary cities" that protect people who are in the country illegally.

Officials in New York and Los Angeles - the country's largest cities - have remained distant from US immigration authorities seeking to deport undocumented immigrants.

"We are not going to sacrifice a half million people who live among us, who are part of our community," New York Mayor Bill de Blasio said.

"We are not going to tear families apart," he vowed.

Meanwhile in Los Angeles, a spokeswoman for Mayor Eric Garcetti said "we comply with federal immigration agencies, but insist that detainer requests be handled constitutionally".

"It is Mayor Garcetti's sincere hope that no president would violate those principles, the very foundation of our nation, by taking punitive action on cities that are simply protecting the well being of residents," Connie Llanos, the spokeswoman told Reuters.

Trump has vowed to deport 11 million undocumented immigrants and threatened to withhold federal funds from sanctuary cities.

This is something viewed as "dangerous" by De Blasio.

"We have some bad hombres here and we're going to get them out," he said.

Some 10,000 Syrian refugees welcomed into the country are also in limbo, with the hard-right president-elect firmly against their asylum bids and promising to bar entry to Muslims to the country.