"The pair were seated next to each other, despite being with a large group of friends and were acting really cute together.
Their chemistry on-screen is undeniable and rumour has it that Justin Timberlake and Mila Kunis are an item in real life.
Kunis, 27 and Timberlake who are in London for the European leg of their promotional tour for Friends With Benefits were acting extremely loved up as they dined together.
They were cosying up to each other and she barked at him "Jay" to follow her. It was like a real girlfriend bark," a source said.
"She yelled at Justin across the restaurant in a way that can only mean one thing," the source added.
In March, Timberlake split from his ex-girlfriend of four years Jessica Beil and it didn't take long for rumours to circulate that his growing closeness to Kunis was the reason.
The pair certainly got close on the set of the film, which sees the Black Swan star spend considerable time between the sheets with the singer.
At the MTV Movie Awards last month, when the pair shocked the audience by publically groping each other.