Vice President Mike Pence to speak at anti-abortion demonstration in Washington DC

March for Life held each year by protesters marking anniversary of landmark 1973 Supreme Court decision to legalise terminations

Vice President Mike Pence speaks at the Republican congressional retreat in Philadelphia (Matt Rourke/AP)

Vice President Mike Pence has agreed to speak at Friday's March for Life, the anti-abortion demonstration held each year in Washington, organisers announced.

In a statement late Thursday, the March for Life organisation said neither a president nor a vice president has ever spoken at the event, now in its 44th year. One of President Donald Trump's top advisers, Kellyanne Conway, is also on the list of speakers.

The president of the March for Life organisation, Jeanne Mancini, called Pence “a friend and champion of the pro-life cause his entire career” - first as a congressman, then as Indiana governor and now as vice president.

Organisers had said earlier in the week that they were expecting an appearance by a “surprise VIP guest.”

Mancini also said in the statement that those taking part in Friday's rally are “bound to leave the March for Life even more energised” because of the vice president's planned appearance and a new administration's support for their cause.

The organisation has predicted tens of thousands of demonstrators would rally on the National Mall starting around midday Friday before marching to the Supreme Court.

The March for Life is held each year by protesters marking the anniversary of Roe v. Wade, the landmark 1973 Supreme Court decision legalising abortion nationwide.

Americans remain deeply divided on the issue. The latest Gallup survey, released last spring, found that 47 percent of Americans described themselves as pro-choice and 46 percent as pro-life. It also found that 79 percent believed abortion should be legal in either some or all circumstances.

AP