Australian researchers have issued a health warning over seagulls after their study revealed the birds carry antimicrobial-resistant bacteria.

The WA Murdoch University researchers examined 562 faecal samples taken from silver gulls across the country.

They found more than 20% carried bacteria resistant to two commonly used antimicrobial drugs.

Overall 22% had extended-spectrum cephalosporin-resistance and 24% had fluoroquinolone-resistant Escherichia coli.