Posters implying Adrian Delia's PN leadership is good for the party's political rivals were affixed to the front of Labour Party clubs across the island overnight.
The A4 posters feature a mock masthead of General Workers Union newspaper It-Torċa, a photo of Dr Delia and the headline "Give Adrian Delia room to work".
That headline is the same as that featuring on a separate set of anonymous posters which appeared on the facades of Nationalist Party clubs earlier this week.
Posters were stuck to Labour Party clubs across Malta and Gozo, from Qala to Attard.
The anonymous group behind the poster campaign said Dr Delia had "strong connections to people very close to the Labour Party" and predicted that PL media would leap to his defence on Sunday.
"Just as we knew we would be in government for as long as Alfred Sant was leader of the Labour Party, they know that as long as Delia is our leader, we will be stuck in Opposition," the group said.
"If we go into a general election with Delia as our leader, we risk turning the country into a dictatorship with a government powerful enough to change the constitution as it wishes," they argued.
The Sunday Times of Malta has reported that PN MPs will be meeting with Dr Delia on Tuesday, when they will be expecting him to announce that he is stepping down as party leader.
At a parliamentary group meeting held earlier this week, just a handful of PN MPs reportedly stood by the party leader.
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