(Reuters) - The Ambassador Bridge, a busy international border crossing linking Windsor, Ontario, with Detroit, was closed Monday night after U.S. authorities received a telephone threat, according to the private company that owns the span.

The shutdown comes less than a week after the Detroit Windsor Tunnel, a nearby cross-border route, was closed by a bomb hoax.

In a statement, the Detroit International Bridge Company said Detroit police received the threat shortly before 8 p.m. EDT (0000 GMT).

The company said the threat was "similar" to the one that closed the tunnel last week -- but provided no additional details. It said it expected the bridge would re-open soon.

Neal Belitsky, the president of the privately owned company that operates the tunnel, told Reuters Monday's bridge shutdown was also the result of a bomb threat. But Canadian and U.S. police did not immediately confirm a bomb threat.

Scott Vetor, a supervisor with the Windsor Police, said traffic was being diverted to the Detroit Windsor Tunnel as well as the Blue Water Bridge, which links Port Huron, Michigan, with Sarnia, Ontario.

The Ambassador Bridge, which opened in 1929, is the busiest commercial border crossing in North America and is a particularly important route for commercial traffic.

More than 25,000 vehicles, many of them trucks, use it every day to pass over the Detroit River.

The 7,500-foot (2,286-meter) bridge is owned by Detroit billionaire Manuel "Matty" Moroun.

(Reporting by James B. Kelleher in Chicago; Editing by Philip Barbara and Lisa Shumaker)