US Vice President Kamala Harris said Tuesday that Washington "must respond" to attacks by El Salvador's leadership on the independence of its judiciary, and more broadly to the corruption that plagues Latin America.

"This weekend, we learned that the Salvadoran parliament moved to undermine its nation's highest court," she said while speaking at the annual Washington Conference on the Americas.

"An independent judiciary is critical to a healthy democracy and a strong economy. On this front, on every front, we must respond," she said, without specifying what form of response she was considering.

A political storm is shaking El Salvador after the parliament voted to dismiss the Supreme Court judges who are hostile to President Nayib Bukele, a decision described as a coup by the opposition and which is causing international concern.

Harris, who has been tasked by US President Joe Biden with handling the sensitive issue of immigration to the US, has more broadly promised comprehensive action against the "root" causes of the influx of migrants at the border with Mexico.

She has listed corruption, violence, poverty, lack of economic opportunity and lack of climate adaptation as being among those causes.

"We will not make significant progress if corruption in the region persists," she added.

Harris pledged to adopt a strategy involving local governments, the international community, private actors and civil society, without going into detail.

Harris also confirmed that she would travel within a month to Guatemala and Mexico for her first trip as vice president.