By Steve Holland and Jeff Mason

NEW YORK (Reuters) - Democratic presidential nominee Hillary Clinton on Wednesday defended her handling of classified information from a private email server at a televised "commander-in-chief" forum that paired her with Republican Donald Trump in separate appearances.

Clinton began the NBC forum saying her long experience in government as a U.S. senator and secretary of state made her uniquely qualified to serve as president. She said she had "an absolute rock steadiness" to be able to make tough decisions.

But moderator Matt Lauer doggedly pressed her about her handling of emails from a private server as President Barack Obama's first-term secretary of state. The issue has raised questions about whether she can be trusted to serve as president.

Clinton said none of the emails she sent or received were marked top secret, secret or classified, the usual way such material is identified. FBI Director James Comey had said she was "extremely careless" in her handling of classified material but decided not to prosecute her.

"I did exactly what I should have done and I take it very seriously, always have, always will,' she said.

Appearing on the second half of the hour-long show, Trump quickly abandoned Lauer's entreaties to avoid attacking his opponent and focus on what he would do if elected president on Nov. 8.

She's been there for 30 years," Trump said. "We need change, and we need it fast."

The event at the Intrepid Air and Sea Museum in New York offered a prelude of how they will deal with questions on national security issues in their three upcoming presidential debates.

The event brought together the meticulously prepared Clinton and Trump, a New York businessman whose brash, freewheeling style has allowed him to dominate the headlines for months.

Clinton said she regretted her decision as a U.S. senator from New York to vote in favor of the 2003 Iraq war and said Trump had been in favor of it as well. Trump has condemned the war during his presidential campaign and said he would avoid lengthy conflicts in the Middle East.

On the U.S. intervention in Libya in 2011, Clinton rejected Trump's criticism of her support for the effort as secretary of state.

"Permitting there to be an ongoing civil war in Libya would be as threatening and as dangerous as what we are seeing in Syria," she said.

She said U.S. policies under her leadership at the State Department had helped promote security.

"We made the world safer," she said.

(Additional reporting by Amanda Becker and Alana Wise in Washington and Gina Cherelus and Jonathan Allen in New York; Editing by Alistair Bell and Peter Cooney)