Lebanon considers itself at war with Israel and it is illegal for Lebanese citizens to cross the heavily-fortified border into Israel or have any kind of contacts with Israelis.

The Israeli military confirmed that a Lebanese citizen crossed the border into Israel today and was detained.

The military statement said the 35-year-old man crossed the border at the Sheik Abbad Hill, about 80 kilometers (50 miles) southeast of Beirut. It said the man, Abdul-Latif Yassin, was taking tranquilizers because of family problems.

The Lebanese army said it was investigating the case and working for the return of the man in coordination with U.N. peacekeepers based in southern Lebanon.

U.N. officials were not immediately available for comment.

The incident comes two months after three Lebanese men suspected of spying for Israel fled into the Jewish state through the border.

Lebanese authorities have so far charged more than 50 people, including two army colonels, with collaborating with Israel.

Those arrested have all been accused of providing intelligence to Israel on the militant group Hezbollah, which fought a 34-day war with the Jewish state in 2006 that killed around 1,200 people in Lebanon _ most of them civilians _ and 160 in Israel.