Hilary Swank claims fans get ''angry'' she isn't Jennifer Garner.

The 43-year-old actress is frequently mistaken for the former 'Alias' star but autograph hunters just assume her denial is because she doesn't want to stop and pose for pictures with them.

She said: ''People get angry at me because they think that I'm just trying not to sign an autograph for them or take a picture.

''They'll be like, 'Oh God, I'm such a big fan. I loved you in Alias.' And I'm like, 'Oh, it's not me.' And they're like, 'Oh no, please, I know you're busy with your family but please!' ''

The 'Trust' star admitted the requests can be so persistent, she sometimes gives in and poses as the 45-year-old actress to stop them going away and badmouthing Jennifer to other people.

Speaking on 'Conan', she admitted: ''They actually said, 'Don't be a b***h.'

''And I didn't want to give her a bad name , so I took a photo with them and maybe someone will say someday, 'That's not Jennifer Garner.' ''

And it isn't just Hilary who's been caught up in the confusion.

She said: ''I told [Jennifer] and she said, 'Oh my God, I get that all the time too!' I said, 'As Jennifer Garner?' And she said, 'No, as you!' ''

Hilary has only recently returned to the spotlight after taking three years out to care for her ''lovely dad'', Stephen Swank'', after he underwent a lung transplant.

When 'The Late Show' host Stephen Colbert praised her as a great daughter, she replied: ''Well, what a lovely dad he is.''

Though Hilary's dad was initially given a ''short time to live'' without having the transplant, the Oscar-winning actress is thankful he is now ''thriving and well''.

She said: ''He's great, thank you for asking. For those of you who don't know, my dad got a lung transplant. It's the hardest surgery a person can undergo and I thank all the people that make themselves a donor, it saves lives.

''They had given him a short time to live if he didn't get a lung transplant and thankfully he got one and he's alive and thriving and well.''