Is there a petrol resistant sealant paste?

The fuel tap on The Scream has a slight leak. I think it is from where the tap mates against the tank itself. I have replaced the rubber o-rings but still there's a weep. I have tightened the bolts as much as I dare without stripping threads.
My lazy instinct is to try a silicone-type sealant. I know that silicone is soluble in petrol, so is there a product which is petrol -proof?.

Curil T2
Supposedly it is petrolproof, but no first hand experience.

Just googled it and checked the data sheets:

"Resistance resistant to mineral oils (also with additives), synthetic oils and greases, gasoline and diesel fuels,"

£12 per tube on Amazon

plastic passing super steal fixed a hole in the corner of my old XJ9 petrol tank. Not sure how well it will behave around orings, threads and if you'll ever get the tap out again mind.

I'd cut up a bit of a milk box, punch some holes in it and put it in between. OR even better use an old innertube. (They will dissolve over time though...)