German Chancellor Angela Merkel has rejected Pakistan's request for supply of air-independent propulsion (AIP) systems for Pak Navy's submarines which would have enabled them to stay underwater for weeks, reports Hindustan Times.

Without AIP systems, Pakistan's diesel submarines have no option, but to come up to the surface almost every second day to capture atmospheric air, which is imperative to keep the diesel engines working underwater. This makes Pakistani submarines running into risk of detection.

The development comes as a major setback for Pakistan's bid to modernise its submarines, even as India last year achieved major headway in it by developing its own land-based prototype of an AIP to be operated on diesel submarines of the Indian Navy.

India has said that once deployed on the submarines, the domestically-built AIP systems would have a "force multiplier effect on the lethality of a diesel-electric submarine."

A top German security council headed by Chancellor Angela Merkel turned down Pakistan's request and conveyed its decision to Pakistan's embassy in Germany on 6 August.

It is believed that the decision came as an outcome of a hard stance on Pakistan's role in promoting terror and it's failure to cooperate in identifying the perpetrators behind a truck bomb attack on Germany's Embassy in Kabul back in May 2017. As many as 150 people died in the the dastardly terror attack.

The bombing was linked to the Haqqani Network which is known to be supported and directed by Pakistan's nefarious deep state.