The Norway international will join the capital club on July 1 on a four-year deal worth £2.2million.

A statement on the club's official website, www.asroma.it, read: "AS Roma announce they have reached an agreement with Liverpool Football Club for the acquisition of the sporting rights of the player John Arne Riise with effect from July 1 2008."

The statement continued: "AS Roma will also pay Liverpool Football Club the following sums: 100,000 euros [£79,250] per season should Roma qualify for the UEFA Champions League in 2009/10 and 2010/11.

"Furthermore, Liverpool FC will also receive 75,000 euros [£60,000] for every 25 official matches the player participates in, up to a maximum of 300,000 euros [£237,550]."

Riise leaves Merseyside after seven seasons with Liverpool, whom he joined from Ligue 1 side Monaco in 2001.

The 27-year-old won the the Champions League in 2005 and the FA Cup in 2006 in his time at Anfield.

Riise, noted for his fierce shot and also effective in midfield, was a regular under former manager Gerard Houllier and in the early years of current boss Rafael Benitez's reign.

He established a reputation for spectacular goals, including one after just 45 seconds of the 2005 Carling Cup final against Chelsea and one in the following year's FA Cup semi-finals, the Blues again the opponents.

However, his 2006-07 campaign was overshadowed by an incident involving former team-mate Craig Bellamy at a training campaign in Portugal, for which the Welshman was disciplined.

He endured an indifferent 2007-08 campaign, the nadir being when he scored an own goal in the final minute of his side's Champions League semi-final first leg against Chelsea.