Thousands of mourners are flocking to pay their last respects to former U.S. president Ronald Reagan as he lies in state in his presidential library in California.

The flag-covered casket arrived at the presidential library in Simi Valley on Monday for the start of two days of public viewing of the closed casket.

By Tuesday afternoon, more than 50,000 had come to view the coffin under the watchful eyes of a five-man honour guard. With so many people in line, viewing hours were extended to 1 a.m. PT Wednesday.

California Gov. Arnold Schwarzenegger and his wife Maria Shriver were among the first to pay tribute, shortly after the casket arrived Monday. Reagan's widow, Nancy, dressed in black with a string of pearls, accompanied the casket in a motorcade, along with by her children, Ron and Patti.

Following the California viewing, Reagan's body will be flown to Washington on Wednesday, where a formal funeral procession will be held in the evening from Andrews Air Force Base.

His body will then lie in state at the Capitol Rotunda until Friday. A state funeral will be held on Friday at 11:30 a.m. ET at the National Cathedral in Washington.

The day has been designated a day of mourning in the country. The memorial observances have been designated a National Special Security Event, which means the Secret Service will be in charge of a federal plan to maintain security.

President George Bush will deliver the eulogy at the funeral. Among the honourary pallbearers selected are:

• Former Canadian prime minister Brian Mulroney
• Frederick J. Ryan Jr., chairman of the board of the Ronald Reagan Foundation
• Merv Griffin, entertainer and family friend
• Charles Wick, head of the U.S. Information Agency during the Reagan administration
• Michael Deaver, one of Reagan's top White House advisers
• Dr. John Hutton, Reagan's longtime physician.

Former Soviet leader Mikhail Gorbachev will be among the mourners, as will former British prime minister Margaret Thatcher, and German Chancellor Gerhard Schroeder.  Governor General Adrienne Clarkson will represent Canada.

The body will then be returned to Reagan's library for a private burial service. He will be buried in a crypt on a hillside overlooking the Pacific Ocean, as he has requested.

The memorial above will read these three line written by Reagan: "I know in my heart that man is good. That what is right will always eventually triumph. And there's purpose and worth to each and every life."

Reagan died on Saturday at the age of 93, surrounded by his family at his California home. He had been out of the public eye for almost a decade, ever since he revealed he was suffering from Alzheimer's disease.

In their first comments since his death, the Reagan family thanked Americans for the messages of condolence they have sent and their outpouring of sympathy.

"As you can understand, the family is in deep mourning over the loss of a husband, a father, a grandfather and their hero," said family spokeswoman Joanne Drake, who read the Reagan statement on Sunday.

Drake said that while this is a sad time for his widow, "there definitely is a sense of relief that he is no longer suffering and has gone to a better place."