Question Summary:
I want to ask that in our village we have a very old jamia mosque. Now we want to re-construct and we have started the construction few days before. When we remove the old structure and start diging underground for blocks we found some graves one side of the mosque.

Question Detail:

I want to ask that in our village we have a very old jamia mosque. Now we want to re-construct and we have started the construction few days before. When we remove the old structure and start diging underground for blocks we found some graves one side of the mosque.

We asked many old people about it whether it was a graveyeard or not, but no one give any clue about this. Now I want to ask can we construct new mosque on the same place or not.

Answer :

In the name of Allah, Most Gracious, Most Merciful
Assalaamu `alaykum waRahmatullahi Wabarakatoh
It is permissible to construct the masjid on the same site since the existence of the graves was previously unknown and it is an unrecognized area for burial by the community, i.e. the site is not recognized as a graveyard and burials do not take place there. However, if the graves dug up are those of disbelievers and some remains (bones, etc.) are found, those remains must be removed. 
وصار ترابا جاز دفن غيره في قبره وزرعه والبناء عليه
(Raddul Muhtar, 2/234, HM Saeed)
 
وإن بقي من عظامهم شيء تنبش وترفع الآثار وتتخذ مسجدا ، لما روي { أن مسجد النبي صلى الله عليه وسلم كان قبل مقبرة المشركين فنبشت }
(Raddul Muhtar, 2/234, HM Saeed
(Ahsan Al-Fatawa, 6/409, HM Saeed)
And Allah knows best
Wassalam
Ml. Asif Umar,
Student Darul Iftaa
Checked and Approved by:
Mufti Ebrahim Desai
Darul Iftaa, Madrassah In'aamiyyah