U.S. citizens in India have been warned that a possible al Qaeda attack may be in the works.

The email warning sent by the U.S. Embassy in Mumbai to American citizens in India urged them to be very cautious in public in the coming week leading up to the country's Independence Day celebrations.

The warning comes exactly one month after a series of train bombs in Mumbai killed over 170 people. The coordinated attacks followed much the same pattern as was seen in the Madrid train bombings and the London attacks last summer.

The Indian government has downplayed the threat. A top Indian bureaucrat in the Ministry of Home Affairs, VK Duggal, described the warning as innocuous and routine. He said such warnings are routinely shared at the official level. He also reiterated that in the lead up to the Independence Day celebrations a high alert already is in place.