Foreign Secretary Tehmina Janjua has termed the acquittal of four of the individuals accused in the Samjhota Express bombing case a "historic injustice", the Foreign Office (FO) said on Thursday.

A day after a special National Investigation Agency (NIA) court in India's Haryana state acquitted the quartet, Janjua "briefed the diplomatic corps in Islamabad on the injustice done to the 44 Pakistani victims of the 2007 Samjhota Express terrorist attack".

As per the FO press release, the foreign secretary questioned how the Indian court could acquit the suspects, including Swami Aseemanand, whom the FO branded the "mastermind of the heinous attacks and an activist of the Hindu terrorist organisation, RSS who had publicly confessed his involvement".

In February 2007, alleged Hindu extremists had bombed the Samjhota Express, killing 68 people, at least 42 of whom were Pakistanis.

The explosions ripped through the train during its transit through Panipat on its way to Lahore from Delhi.

Janjua today recalled that the NIA had itself earlier issued charge sheets to the perpetrators of the attack.

Additionally, she said that the Indian media had extensively reported about the connections between the Samjhota Express terrorist attack and "Hindu extremists including Lieutenant Colonel Purohit and Sadhvi Pragya Singh Thakur, who were subsequently arrested in October 2008, including [the] provision of RDX (research department explosive)."

"On 18 December 2010, Swami Aseemanand, the mastermind of the attack confessed publicly before the New Delhi court that Hindu terror outfits were behind the blasts," the press release added.

The foreign secretary stressed that despite Pakistan's repeated requests for a fair trial and "expeditiously bringing the perpetrators to justice," after a lapse of over 11 years, Indian courts had exonerated the accused.

The press release noted that Pakistan had already registered a "strong demarche" with the Indian high commissioner yesterday against the acquittal.

"The Indian decision to gradually exonerate and finally acquit the perpetrators despite the presence of clear evidence against them, is a reflection of India’s callous insensitivity to the plight of the 44 families of the deceased Pakistanis, who have been waiting for more than a decade to see these terrorists brought to justice. It also demonstrates how India protects terrorists who publicly confessed their odious crimes," the press release stated.

It added that the acquittal was also reflective of the Indian state policy of "promoting and protecting terrorists".

"This state patronage of extremist Hindutva ideology is not only detrimental to the lives and liberty of all minorities in India, but is also dangerous for peace and security in the region."

Janjua also expressed "great concern" that India continued to commit "gross human rights violations" in the Indian-occupied Kashmir.

Furthermore, she expressed concern that a "frenzy" was created against Pakistan to "gain benefits in domestic politics", the Foreign Office said in its statement.

She urged all "fair-minded people" to call on India to explore all "judicial remedies so that the terrorists are brought to justice."