Obama to announce immigration action in Thursday night speech
US President Barack Obama delivers a prime time address from the White House on September 10, 2014 in Washington, DC (AFP Photo/Saul Loeb)

U.S. President Barack Obama is expected to announce details of his executive action on immigration in a Thursday night speech ahead of travel to Las Vegas on Friday, sources close to the administration said.

One source familiar with the White House plan on Wednesday said Obama's action aims to provide relief from the threat of deportation for 5 million undocumented immigrants. It will also strengthen border security, address high-skilled foreign workers, and expand assistance to undocumented residents brought to the United States as children, the source said.

Separately, labor union sources said Obama was expected to lay out details of the plan in Thursday's speech.

(Reporting by Richard Cowan and Amanda Becker; Editing by Roberta Rampton and Susan Heavey)