ISLAMABAD, AUGUST 6:  Authorities in Pakistan have put in place special security measures in major cities, including Islamabad, citing threats ahead of the annual Eid festival marking the end of the holy Muslim month of Ramadan. The move comes just days after a major jailbreak in a northwestern city that freed nearly 250 prisoners, including “dangerous terrorists.”

In the wake of rising militant and sectarian attacks in recent years, security is usually tightened across Pakistan in the closing days of Ramadan, when people often crowd major mosques to worship round the clock.

However, a top police officer in Islamabad, Jamil Hashmi, acknowledged that this year special security measures have been put in place, citing “certain threats”. He did not elaborate and said that police teams, assisted by paramilitary forces, also scoured forests in the Margalla hills surrounding the capital city.

“Close to the Eid [festival] we do the same every year because about 1,500 people are sitting in the Faisal Mosque and we have to take care of them as well. There are certain threats as well so keeping in view the threats, we have made extraordinary arrangements. We have made search operations in the Margalla hills. On top of the hills there are some new pickets [troop deployments]," said Hashmi.

Some Pakistan officials are reported saying reinforcements also have been sent to protect sensitive locations in Islamabad that face a security threat. Among them are the parliament building and the Faisal Mosque, the largest in Pakistan.

Despite heightened security, a bomb exploded inside a passenger train traveling between Lahore and Karachi. More than a dozen people were wounded.  There are no claims of responsibility.

Suspected Taliban militants have unleashed a bloody insurgency that has killed thousands of Pakistanis in recent years while Sunni Muslim extremists have stepped up deadly attacks on the nation's minority Shiite community.

It is unclear whether the security alert is meant to defend against a specific target or whether it is a reaction to last week’s massive jail break in northwestern Pakistan.

Heavily armed local Taliban fighters disguised as police assaulted a prison in Dera Ismail Khan and freed nearly 250 inmates.

Pakistani officials say the escapees included around 45 they considered “dangerous terrorists”. The majority remain at large.

That jail break and similar attacks on prisons in Iraq and Libya prompted the international police agency, Interpol, to the put the world on security alert. In addition, the United States and other Western governments have closed embassies in recent days in several countries in the Middle East and Africa because of security threats.