A U.S. State Department spokesman said on Tuesday that Iranian President Mahmoud Ahmadinejad's plan to tour southern Lebanon is "not a good idea."

He also accused the Islamic republic of undermining Lebanon's sovereignty.

"We don't think that his (Ahmadinejad's) travel to that part of Lebanon is a good idea," said State Department spokesman Philip Crowley, although he admitted that it is up to the Lebanese government to make the decision.

Ahmadinejad will arrive in Beirut on Oct. 13 for a two-day official visit. He is scheduled to tour southern Lebanon and inspect the town of Maroun al-Ras, which witnessed severe clashes between Hezbollah and Israel in 2006.

Crowley confirmed that U.S. Secretary of State Hillary Clinton has expressed concern on the visit to Lebanese President Michel Suleiman as the two met on the sidelines of the UN meetings in New York in late September.

He alleged that Iran, through its association with groups like Hezbollah, is actively undermining Lebanon's sovereignty.

"We believe that whatever you decide to do should be in light of making sure that the Lebanese government continues to demand that Iran or any other country respect its sovereignty," he said.

Ahmadinejad's planned visit has been criticized by Israel as a provocation, prompting the Jewish state to tighten security on borders with Lebanon.