Michael Sheen has shut down rumours he was in a relationship when he met his now-pregnant girlfriend Anna Lundberg.

The 'Good Omens' star felt the need to take to his social media sites over the weekend after speculation began to swirl that he had cheated on his ex-partner Aisling Bea - whom he split from last summer - when he started to pursue his current 25-year-old lover.

He wrote on Twitter: ''Wouldn't normally respond to this kind of thing but for the sake of people I love and who have more important things to focus on right now...

''I was single from the beginning of last summer until I met my partner Anna who is now going to have our baby. Just for the record. Thanks.''

The 50-year-old actor confirmed he was expecting a baby with Anna last month when he wrote online that they were having a ''little angel.''

He said: ''Very happy to let everyone know that my partner Anna and I are expecting a little angel of our own. (Just to be clear - we're having a baby!) #nottheantichrist (sic)''

He later said during a television interview that he was excited about his 20-year-old daughter Lily Mo, whom he has with his ex-partner Kate Beckinsale, having a step-sibling on the way.

He explained: ''It's very exciting. My other daughter is 20 years old. It's been a while since I've gone down this path. But it's fantastic, it's really exciting.''

Michael previously confessed he is ''in awe'' of his daughter.

He said: ''She changed my life when she was born but as Lily's become more of her own person with her own independent life, I've seen how much I thoroughly enjoy her company. She's given me an insight into the pressures young people are facing - Lily's 20 now - and that roller coaster ride of growing up with social media. As I watch her work her way through these pressures with courage, tenacity and resilience, I'm really in awe of her.''