Updated

Tunisia's main trade union said Wednesday that the government had notified it of "serious threats" to its leaders aimed at undermining its efforts to broker an end to a lingering political crisis.

"The union's management has been informed of the existence of serious threats targeting its leaders... with the information coming from the relevant departments of the interior ministry," the UGTT said on its Facebook page.

The powerful trade union has been leading mediation efforts to end two months of political deadlock sparked by the assassination in July of opposition MP Mohamed Brahmi, an attack blamed on radical Islamists.

It said the threats were designed to hamper the proposed "national dialogue" between Tunisia's Islamist-led government and the opposition to find a compromise and overcome the current impasse.

The UGTT gave no further details about the origin or nature of the threats.

It has previously accused the League for the Protection of the Revolution, a controversial militia with ties to the ruling Islamist party Ennahda, of attacking a gathering outside its headquarters, which left several unionists wounded.

Since Brahmi's murder, political activity in Tunisia has been ground to a halt, with the opposition demanding the ruling coalition's immediate resignation and calling for a nationwide campaign of protests.

Ennahda has agreed to step down and allow the formation of new government but only once a compromise has been reached on key political issues, notably the draft constitution.

The UGTT said on Saturday that the ruling Islamists, whom it had previously accused of dragging their feet, had fully accepted its transition plan, which includes a three-week deadline for the formation of a cabinet of independents after the launch of national dialogue.

An Ennahda spokesman confirmed that the Islamists were "ready to enter into dialogue with all parties", adding that the talks could begin this week, but he said no date had been set.

Tunisia remains without a new charter, functioning state institutions or a timetable for fresh elections more than two and half years after the uprising that toppled former strongman Zine El Abidine Ben Ali and touched off the Arab Spring.