ANKARA — Turkey's president says authorities suspected the outlawed leftist group that bombed the U.S. Embassy in Ankara was planning an attack, but did not have enough information to prevent it from happening.

The Revolutionary People's Liberation Party-Front, or DHKP-C, has claimed responsibility for Friday's suicide bombing of the embassy, which killed the attacker and a Turkish security guard and seriously wounded a former Turkish television journalist.

President Abdullah Gul said at a news conference Monday that Turkish police and intelligence officials were on high alert about the DHKP-C, knowing it was seeking to carry out an attack of some sort but didn't know where or when.

In its claim of responsibility, the Marxist group denounced imperialism but gave no specific reason for targeting the U.S. Embassy.