Nuevo Laredo is located just across the border from Laredo in Texas
An explosive device has been thrown at the US consulate in the Mexican city of Nuevo Laredo, US officials say.
The blast caused some damage but no injuries. The consulate will remain closed as investigations continue.
There was no indication of a motive but Nuevo Laredo, near the US border, and other cities in the state of Tamaulipas have seen a flare-up in drug violence.
In March, three people linked to the US consulate in Ciudad Juarez in the state of Chihuahua were shot dead.
The motives for those killings remain unclear, but drug gangs are suspected.
The US consulate in Nuevo Laredo said a device was thrown over the wall into the compound late on Friday night, damaging some windows.
Nuevo Laredo, located just over the border from Laredo in Texas, and other parts of the Tamaulipas state have seen an increase in violence in recent weeks.
This is blamed on a split between the Gulf cartel and their former allies, Los Zetas who are battling for control of smuggling routes into the US.
Drug-related violence has left some 18,000 people dead in Mexico since 2006.
During a visit to Mexico in March, US Secretary of State Hillary Clinton pledged increased support for Mexico in the fight against drug gangs.
She said more would be done to cut US demand for drugs and the flow of profits and guns into Mexico.