WASHINGTON (Reuters) - A U.S. State Department video of a press briefing about secret U.S.-Iran nuclear talks was deliberately edited but there is no evidence to suggest the cut was intended to hide information, a U.S. spokesman said on Thursday after further details were released of an investigation into the incident.

"We are confident the video of that press briefing was deliberately edited," State Department spokesman John Kirby told reporters, adding: "What we were not able to determine is why the edit was made in the first place. There's no evidence to suggest it was made with the intent to conceal information from the public."

The excised portion of a Dec. 2, 2013, briefing included a question about whether an earlier spokeswoman for the department had misled reporters about whether the United States was holding secret direct nuclear talks with Iran.

The State Department initially said it was caused by a "glitch" but later said it was a deliberate omission.

Kirby said the investigation by the department's Office of the Legal Adviser could not rule out that a technical glitch might have deleted the portion of the video because of the "choppy nature of the cut."

He said the findings had now been shared with Secretary of State John Kerry and with congressional members.

(Reporting by Lesley Wroughton; Editing by James Dalgleish)