Qatar had donated EUR 15m to kick-start the construction of a mosque and cultural centre on the northern edge of the city centre, which began in 2015.
But after the main structures of what will become the first mosque in Slovenia were erected, works ground to a halt since the community ran out of money to fully fit out the buildings.
Grabus said Qatar had already donated a million euros this year and would transfer the remainder to pay the bills once the main contractor finishes the second stage of construction.
But even then another EUR 2.4m will be needed to install the interior equipment. Grabus was hopeful the money would be provided by members of the community.
Slovenian Muslims have already donated about EUR 4m for the cause, with about the same amount of money coming from Bosnia, he said.
The entire project is valued at EUR 35m, up from the initial estimate of EUR 15m.
Given that Qatar has provided the bulk of funding, there have been fears that it may in exchange try to impose a stricter version of Islam than practised by the Slovenian Muslims, most of whom hail from Bosnia-Herzegovina.
But Grabus said this fear was unfounded, as there were no strings attached to the money.
He said the Slovenian leadership would be fully in charge of all activities, but "it is true that certain groups close to politics have tried to discredit us from the start."
There are no recent data on the number of Muslims in Slovenia.
In the last census that included a question about religious affiliation, in 2002, almost 50,000 identified themselves as Muslims, but the number is believed to have grown significantly since then.
