White House officials have tried to pressure US immigration authorities to release migrants detained at the border into so-called sanctuary cities such as San Francisco to retaliate against Donald Trump’s political adversaries, the Washington Post reported on Thursday.

The Post, which reviewed emails on the issue and spoke to unnamed officials at the Department of Homeland Security, said the White House proposed the measure at least twice in the past six months. Sanctuary cities are those where local officials decline to hand over illegal immigrants for deportation.

The White House and Department of Homeland Security did not immediately respond to a Reuters request for comment on the report.

But the Post quoted a White House official as saying the proposal was no longer under consideration, calling it “just a suggestion that was floated and rejected, which ended any further discussion”.

Trump administration officials proposed the measure in November as a caravan traveled through Mexico with mostly migrants from Central American countries toward the southern US border. The proposal emerged again in February during a standoff with Democrats over funding the president sought to build a wall on the border, one of the signature issues of his 2016 election campaign and presidency.

The Post said a 16 November email broached the proposal, asking officials at different agencies whether members of the migrant caravan could be detained at the border, then bused to “small- and mid-sized sanctuary cities”, where local officials refuse to hand over illegal immigrants for deportation.

The House speaker Nancy Pelosi’s district in San Francisco was one of those the White House considered targeting, the Post cited the DHS officials as saying.

Ashley Etienne, a spokeswoman for Pelosi, denounced the administration for its “cynicism and cruelty” over the plan.

“Using human beings including little children as pawns in their warped game to perpetuate fear and demonize immigrants is despicable, and in some cases, criminal,” she said, adding that Americans had “resoundingly rejected this administration’s toxic anti-immigrant policies”.