Chennai, Nov 18 (IANS): Norwegian World chess champion Magnus Carlsen and the Indian title challenger Viswanathan Anand Monday signed a peace treaty after fighting for over six hours and making 122 moves in seventh round.

The game was one of the longest in the history of world chess championship.

At the end of the seventh round, Carlsen was leading the 12-round match with four points to Anand's three points.

Carlsen opened the game pushing his king pawn two squares and Anand did the same. But soon Anand decided to go for Berlin defence variation.

Both the players made their moves very fast.

On move six, Carlsen exchanged his white bishop for Anand's knight.

Two moves later, Carlsen went for queen exchange to avoid Anand's queen chasing his king.

"The players actually followed my recent game vs. Radjabov in Tashkent Grand Prix tournament, where I was putting a lot of pressure throughout the game. Anand made an improvement, but I have the feeling he wasn't prepared deeply enough after that," World number 7 and Grandmaster Anish Giri told IANS.

"The choice of opening (Berlin defence) was good by Anand. But slowly white's position turned for the better," World number 26 and Indian Grandmaster P. Harikrishna said.

The players steadily exchanged their pieces and on the 27th move Carlsen had a rook, knight, black bishop and four pawns-connected two each on king and queen side.

On the other hand Anand had a rook, knight, white bishop and five pawns-four on his queen side, and one on the king side.

At this stage, the position of Carlsen's pieces on the board were controlling good number of squares and his rook was on the seventh rank restricting free movement of Anand's pieces.

In order of prevent a difficult slow grind, Anand decided to give up his white bishop for Carlsen's two king side pawns.

According to Giri, the Indian ace went for a very solid position a piece down which he assumes to be a fortress.

At this position, Anand had four pawns on his queen side and a rook to Carlsen's two pawns on the queen side, a knight and a rook.

However Anand has to hold on to his rook as his life was riding on that.

While Anand had to play passive moves, Carlsen's knight started hopping around the board and his king also started moving.

However, the Indian tiger defended his position precisely and at one point decided to go for pawn exchange.

After than Carlsen was left with his knight and rook, while Anand had just a rook.

Thought it was theoretically a draw, Carlsen continued to play as if expecting Anand to make a blunder.

But on the 122th move the rooks got exchanged and the players finally agreed to split the points.

"Though it was a tiresome game, the end result is actually a psychological boost for Anand for the next round," Harikrishna said.

The eighth round will be Tuesday with Anand playing with white pieces.