NEW DELHI (Reuters) – The U.S. embassy in India warned American citizens on Friday of possible attacks by al Qaeda in or around New Delhi and Mumbai in the run-up to the country’s Independence Day celebrations next week.

The warning came a day after British police said they foiled a major plot to attack transatlantic airliners, and exactly a month after Mumbai was hit by a series of bomb blasts which killed 186 people and wounded over 700.

The Indian government, however, tried to play down the alert saying it was a routine advisory by a foreign mission to its nationals.

Officials at several other foreign missions, including the British and the German, also said they were not aware of any specific threat.

“We have urged U.S. citizens to keep a low profile, be alert and attentive to their surroundings,” a U.S. embassy spokesman said.

“The embassy has learnt that foreign terrorists, possibly including members of al Qaeda, allegedly intend to carry out a series of attacks,” he said, adding the attacks might occur in or around New Delhi and Mumbai.

The information was gathered by U.S. intelligence agencies and the embassy was working closely with the Indian government, he added.

“Likely targets include major airports, key central Indian government offices, and major gathering places such as hotels and markets,” he added.

India celebrates the anniversary of independence from British colonial rule on Aug. 15 and security has already been stepped up in the capital as well as other major cities.

The festivities have been marred in the past by attacks by Islamist militants fighting Indian rule in disputed Kashmir as well as insurgent groups in the country’s troubled northeast.

Indian officials said the country was anyway on a high alert in the run up to Aug. 15 and they were working with U.S. agencies over the alert, which, they added, was not unusual.

“It is normal for missions to issue advisories when they have any information,” Home Secretary Vinod Kumar Duggal told a news conference. “It’s a very innocuous advisory … to their own staff, to their own employees.”

Some U.S. nationals echoed Duggal’s sentiments.

Stuart Zimble, a humanitarian worker from Philadelphia, said he had received similar warnings in the past “although nothing so specific, about al Qaeda”.

“For me it’s not that unusual,” said Zimble who has lived in New Delhi for over three years. “It’s a relatively safe city, but on big holidays I generally stick close to home.”

Earlier, following the arrests in Britain, security at all 55 airports across India was tightened and hand baggage was not being allowed on certain flights to the West.

On other flights, passengers would be allowed only one piece of hand baggage and all liquids, other than medicines, would have to be checked in, officials said.

Security was also stepped up at vital government installations across the country and 38 elite commandos were deployed at a nuclear plant in the southern state of Tamil Nadu, they said.

Also, police in the Indian capital said they had arrested two men they said were members of Pakistan-based Islamist group Lashkar-e-Taiba late on Thursday from New Delhi’s main railway station after they arrived from Kashmir.

“They were carrying some RDX explosives and weapons. We suspect they planned an attack during Independence Day celebrations,” a Delhi Police spokesman said.

Lashkar has been blamed for several deadly attacks in Kashmir and elsewhere across India in the past, including serial bomb blasts in Delhi last year and the Mumbai train bombings.

Officials in Mumbai said they were taking the U.S. warnings very seriously.

“This warning as well as other factors such as what happened in Britain yesterday and the run-up to Independence Day is making us take this all very seriously,” said D.K. Sankaran, the most senior bureaucrat of Maharashtra state, of which Mumbai is the capital.