Swamy has moved the High Court seeking further probe to ascertain the alleged role of the then Minister of State for Home P Chidambaram in the case.
Justice V P Vaish sought to know how much more time Uttar Pradesh government will take to give a reply.
"This case is of 1987. Last opportunity is given to the respondent no.1 (UP government). Reply be filed in two weeks and the advance copy be supplied to the petitioner (Swamy)," the court said, adding that otherwise it will dispose of the plea while allowing it.
The High Court had in August 2013 sought a response of the UP government while hearing Swamy's appeal which has also challenged the trial court's March 8, 2013 decision dismissing his plea against Chidambaram, Union Minister between 1986 and 1989.
In the appeal, Swamy sought further investigation saying, "it was admitted on the floor of Parliament by the then Minister of State for Home Affairs P Chidambaram that the situation was calm on May 19 to May 22, 1987. Yet the trial judge states it was violent strife.
Sixteen Provincial Armed Constabulary (PAC) personnel are facing trial in the killing of 42 persons in Hashimpura area of UP's Meerut district.
The Supreme Court had transferred the case to Delhi in September 2002 following a petition by the families of the massacre victims and survivors.
A sessions court here had in July 2006 framed charges of murder, attempt to murder, tampering with evidence and conspiracy against all the accused. Three accused PAC personnel have died during the trial.
The trial court had in March 2013 dismissed Swamy's plea for further probe to ascertain Chidambaram's role in the incident saying he has no locus standi and it is only the police who can move an application (for further probe).