LONDON (REUTERS) - Britain's Prince Harry and American actress Meghan Markle have asked a senior US bishop to deliver the address at their wedding next Saturday (May 19).

Harry, grandson of Queen Elizabeth and sixth-in-line to the throne, and Markle, star of US TV drama Suits, will tie the knot next Saturday at Windsor Castle, home to British royals for nearly 1,000 years.

Kensington Palace said the Most Reverend Michael Bruce Curry would join Justin Welby, the spiritual head of the Anglican communion, for the wedding which is expected to be watched by millions of people around the world.

Curry, the 27th Presiding Bishop and Primate of the Episcopal Church, was the first African-American presiding bishop when elected in 2015.

Welby will preside over the exchange of vows, while the service itself will be conducted by the Dean of Windsor.

"The love that has brought and will bind Prince Harry and Ms. Meghan Markle together has its source and origin in God, and is the key to life and happiness," Curry said in a statement.

"And so we celebrate and pray for them today."

Markle was reported to have been baptised by Welby, the Archbishop of Canterbury, in March.

The United States-based Episcopal Church is a constituent member of the global Anglican Communion, of which the Church of England is the Mother Church.

According to its website, Curry has been active in issues of social justice including immigration policy and marriage equality.