The American embassy in Algiers has warned of a possible attack by "an unspecified terrorist group" over the weekend and advised its staff to avoid US-operated hotels.
"As of June 2014 an unspecified terrorist group may have been considering attacks in Algiers, possibly in the vicinity of a US branded hotel," the mission said on its website.
"The US Embassy in Algeria has instructed embassy employees to avoid US owned or operated hotels through the US Independence Day (July 4) and Algerian Independence Day (July 5) holiday weekend."
The statement, dated Wednesday, gave no further details of the possible threat.
Violence attributed to Islamists has declined considerably in Algeria in recent years, after a decade of appalling blood-letting during the civil war of the 1990s.
But groups affiliated with Al-Qaeda in the Islamic Maghreb continue to attack security forces in the eastern Kabylie region, in areas around the capital and in the south.
The last major incident in Algiers took place in December 2007, when twin suicide bombings claimed by Al-Qaeda targeted a government building and the offices of the UN refugee agency, killing 26 people and wounding nearly 180.
Since the 2011 uprisings toppled dictators across the region, Algeria has been increasingly vulnerable to attacks from Mali and Libya, with whom it shares vast desert borders.
In the worst attack on Algerian soil in years, Al-Qaeda-linked militants stormed the In Amenas desert gas plant, 1,300 kilometres (800 miles) southeast of Algiers, in January 2013.
Around 40 foreign hostages, including three Americans, were killed in the four-day siege and army rescue operation that followed.