Speaker Nancy Pelosi says the House of Representatives will file impeachment charges against US President Donald Trump for alleged abuse of power.

“Our democracy is what is at stake, the president leaves us no choice but to act,” the top elected Democrat said.

Mr Trump said Democrats have “gone crazy” and urged them to move quickly if they were going to impeach him.

Democrats say Mr Trump corruptly made military aid to Ukraine conditional on it investigating his rival, Joe Biden.