Guterstam is under contract with Brommapojkarna, whom he joined in 2002, but the club finished bottom of the Swedish top flight in October and his deal is believed to include a relegation release clause which would allow Leeds to sign him on a free transfer.
The forward broke into Sweden's national team on a tour of South America last year and he won his first cap during a friendly with Ecuador in January.
His opportunities have been restricted by the number of experienced strikers available to Sweden, including Inter Milan's Zlatan Ibrahimovic and ex-Aston Villa forward Marcus Allback.