Nicolas Burdisso got on the scoresheet in the 11th minute followed by Hernan Crespo nine minutes after the break to secure Inter's seventh consecutive league victory.

Roberto Mancini's side are unbeaten since the start of the league season, with 11 wins and three draws, giving them 36 points and a four-point lead on AS Roma, who beat Atalanta 2-1 in Saturday's late game.

Since October 27, Inter have won all their matches including seven in the league, two in the Italian Cup and two in the Champions League.

Apart from the header by Burdisso from a corner and the flick over Siena keeper Alex Manninger in the 54th minute by Crespo for the two goals, Inter also excelled at the other end with Brazilian keeper Julio Cesar saving a penalty from Liechtenstein striker Mario Frick five minutes after the break.

Mancini, speaking to Italian television, said afterwards: "We played better against Reggina (1-0 victory in their last home match), but this game was difficult.

"If Siena had converted their penalty, the complexion of the match could have changed. However we controlled the game well and were able to continue that until the end of the game. It wasn't easy but the boys were up to it."

Inter now hold a 25-point lead over city rivals AC Milan, who started the season with an eight-point penalty and currently sit sixth from bottom.

They are also through to the knock-out stages of the Champions League but need to beat Bayern Munich away on Tuesday to top the group.

Roma are second with Palermo third, nine points off the lead, and Livorno come next a mammoth 16 points behind Inter.

Roma's victory was no easy matter and they had fallen a goal behind by the break following the 19th minute strike from Atalanta's Riccardo Zampagna after a good move.

Lack of discipline in the second half however meant Atalanta conceded two penalties after fouling Simone Perrotta then Francesco Totti and it was the latter who converted both in the 50th and 63rd minutes to complete the fightback.

Before the game, three Atalanta supporters were injured in clashes with Roma fans, and one was in a serious condition in hospital after being stabbed, Ansa newsagency reported.

Two coaches of Atalanta supporters got stuck in heavy traffic and fans got off, probably to walk the rest of the way, about an hour before kick-off. They then came into contact with Roma fans also walking to the Olympic stadium which sparked off the incidents.