Massachusetts-based grocer Market Basket escalated its internal power struggle on Monday, filing for a restraining order in Middlesex Superior Court against two former executives allied with suspended chief executive Arthur T. Demoulas. The company says Joseph Schmidt, its former director of operations, used a master key to enter the chain’s Tewksbury headquarters after hours on 7 August and, together with former grocery director Tom Gordon, has visited dozens of stores to pressure employees to support Demoulas. In the 33-page complaint, Market Basket accuses the pair of waging a “campaign of intimidation and defiance” intended to slow work or spark a walkout, echoing the 2014 labor unrest that roiled the grocer. The board also alleges Demoulas orchestrated recent opinion pieces, leaked documents and employee letters critical of management ahead of a court-ordered mediation set for 3 September. Attorney Harvey Wolkoff, hired by the board, warned that such conduct could derail any settlement. A spokesperson for Demoulas dismissed the filing as “scorched-earth tactics,” saying Schmidt merely returned a company car and greeted former colleagues and that neither man engaged in wrongdoing. A hearing on the restraining order is scheduled for Thursday at 10 a.m. The dispute has lingered since May, when Demoulas was placed on leave and an outside law firm began investigating claims he planned a retaliatory work stoppage at the $8 billion family-owned chain.