The dead piglet had the words “Mutti Merkel” (Mother Merkel) daubed on it in red paint, the Leipziger Volkszeitung (LVZ) reported.
“I see this as just a stupid act. I don't know what they mean to say with this, but our mosque construction project will continue,” Dr Rashid Nawaz of the Leipzig branch of the Ahmadiyya Muslim Jamaat (AMJ) organization told The Local.
The piglet was hurled onto the patch of earth sometime overnight from Tuesday to Wednesday, he said.
“Insulting, reviling and smearing a whole religious community is narrow-minded and outrageous,” Leipzig mayor Burkhard Jung told the LVZ on Thursday.
“Leaving a dead pig with the words 'Mutti Merkel' on it isn't just tasteless, but demonstrates fundamental failings of democratic education and conviction,” he added.
'They just lump everyone together'
It's not the first such act against the future mosque site. Unknown perpetrators left bloody pigs' heads on spikes along the length of a path that crossed the lot in November 2013.
“Of course there is tension in Leipzig, people afraid of Islam,” Dr Nawaz said. “But we need to differentiate. We at AMJ categorically reject violence. But these people don't understand that, they just lump everyone together.”
AMJ sees itself as a global reform movement within Islam whose motto is "Love for all, hatred for none". It has around 35,000 members in Germany, with more than 39 mosques and 225 congregations, a TV station and a publishing house.
The Leipzig branch has been working together with local Christian churches and pastors to answer residents' questions since the mosque project was announced, Dr Nawaz said.
Just two days ago, the Muslim community held a new year reception for local people to discuss their questions about the mosque. Construction is supposed to begin in September on the €700,000 house of worship.
“I think [engaging with the public] is the only way to give people information and the only way we'll be able to get to know one another and get along. I'm firmly convinced of that,” Dr Nawaz said.
Leipzig is the second city of Saxony in eastern Germany, which currently hosts around 5 percent of Germany's refugee population but accounts for 25 percent of anti-refugee attacks, says refugee advocacy NGO ProAsyl.
Half of refugees in Germany in 3 states (NRW,Bavaria,BW) as 5% of refugees but 25% of attacks against them in Saxony pic.twitter.com/kGdHTC9Quj- Alper Üçok (@AlperUcok) February 25, 2016
The state capital, Dresden, is home to the anti-Islamic Pegida movement, which has been holding largely peaceful weekly demonstrations for over a year against what it calls the “Islamization of the West”.
In recent days attention has once again focused on Saxony after video emerged of a crowd chanting angrily at a busload of asylum seekers arriving in the small town of Clausnitz - causing some of them visible distress.
Just days later, fire broke out in a refugee home in a suspected arson attack in the town of Bautzen.
A group of onlookers actively tried to hinder firefighters from reaching the building, which was not yet inhabited.
Saxony minister-president Stanislaw Tillich has been hard-pressed to defend the state against its critics despite his tough talk aimed at perpetrators in the days following the two incidents.
“I will not allow this Free State of Saxony to be brought into disrepute by a few people who have placed themselves outside the rule of law,” he said on Tuesday.