US biotech company Monsanto has reported a first-quarter profit, compared to a year-ago loss, but said operating results fell on lower US sales of herbicides and seeds.

The St Louis-based company, which makes Roundup herbicide and bioengineered seeds, reported net income of US$60m, or 23 cents a share, compared with a loss of $1.74bn, or $6.59 a share, in the previous year.

Excluding charges, the company posted earnings of $72m, or 26 cents a share, compared with $86m, or 33 cents a share, a year earlier.

Analysts had been expecting earnings of 22 cents a share, reported Reuters.

Monsanto said it expects full-year earnings of between $1.25 and $1.40 per share, excluding items.