The U.S. Embassy in Islamabad on Sunday warned its staff of a possible attack on Americans at a top hotel in Pakistan's capital as the city was already on high alert following a suicide bombing earlier in the week.

The U.S. government is aware of information that “unknown individuals are possibly plotting to attack Americans at the Marriott Hotel in Islamabad sometime during the holidays," the embassy said in a security alert. The advisory banned its American personnel from visiting the popular hotel over the holidays.

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The U.S. mission also urged all personnel to refrain from non-essential travel in Islamabad during the holiday season.

The embassy directive came two days after a suicide bombing in a residential area of the capital killed a police officer and wounded ten others. The explosion happened when police stopped a taxi for inspection during a patrol. According to the police, a rear seat passenger detonated explosives he was carrying, blowing up the vehicle.

Militants with the Pakistani Taliban, who are separate from but allied with Afghanistan's rulers, later claimed the attack.

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Islamabad's administration has since put the city on high alert, banning public gatherings and processions, even as campaigns are ongoing for upcoming local elections. Police have stepped up patrols and established snap checkpoints to inspect vehicles across the city.

A suicide bombing targeted the capital's Marriott Hotel in September 2008, in one of the deadliest such incidents in the capital. Attackers drove a dump truck up to the hotel's gates before detonating it, killing 63 people and wounding over 250 others.