Friday's Stage 19 of the Giro d'Italia has been cancelled because of snow, while stage 20 has been re-routed.

Both stages in the Dolomite mountains have been hit by bad weather but race organisers still hope Saturday's penultimate stage will go ahead.

A 210km route from Silandro to Tre Cime di Lavaredo has been planned with three of the five original mountains cut.

Italy's Vincenzo Nibali leads the race by four minutes and two seconds from Australia's Cadel Evans.

Weather-hit Giro Stage 20: three of five mountain climbs removed

Stage 19: cancelled because of snow

Stage 15: avalanche risk means ascent to Col du Galibier is cut short but race still affected by snow

Stage 14: Climb to Sestriere trimmed because of danger of ice on descent with riders facing snow

Friday's 139km stage was scheduled to be the highlight of the three-week race.

It was due to start in Ponte di Legno and include the famous Gavia and Stelvio passes, taking in the highest point of the race at 2,783m, and finish at the ski resort in Val Martello.

However, with windchill temperatures expected to drop to -20C, organisers decided it was not safe for riders.

Race director Michele Acquarone told BBC Sport: "It was a tough decision on a big stage on a great finish in a great Giro. It was very hard to say no.

"But at 09:30 we contacted every mountain pass on the stage and they said 'no, it can't be done for the safety of the riders and the hundreds of workers'. It was better to say no.

"When you plan a Giro you have the race route, a plan B and a plan C but we can't do all the alphabet.

"On Saturday there is also a change in the route. The San Pellegrino is covered in snow and we're trying to save the finish at Tre Cime."

Stage 20 was set to feature five categorised climbs during a final day in the Dolomites of northern Italy but the Passo Costalunga, Passo di San Pellegrino and Passo Giau have all been omitted from the new route.

The climb of the Passo Tre Croci remains, along with the final climb to the finish at Tre Cime di Lavaredo, weather permitting.

The Giro, which ends in Brescia on Sunday, has been hampered throughout by unseasonal bad weather.

Stage 14's route missed out the climb to Sestriere because it was considered too dangerous to descend in the ice, and an avalanche risk curtailed stage 15's climb up the the Col du Galibier. Several other stages have been hampered by torrential rain.

Analysis Rob Hayles Former GB cyclist, BBC Sport commentator "I'm not surprised race organisers cancelled today's stage - we are in a hotel near where stage 19 was due to finish at 1,800m and there is a lot of snow around - there are plenty of black and white photos of riders battling through snowy mountains in the past but thankfully race organisers have considered the health and safety of the riders. "A lot of them, including Mark Cavendish, will be chuffed. He texted me this morning to say he was disappointed because he was going to go for the points in the intermediate sprint - the sprint was scheduled to come after the two big mountain passes! "Seriously, it is a shame but with Vincenzo Nibali being so dominant I can't see that it will make much difference to the overall outcome of the race." Listen to Radio 5 live's stage 18 podcast

Pre-event favourite Sir Bradley Wiggins pulled out after stage 12 because of a chest infection, while defending champion Ryder Hesjedal also abandoned the race through illness.

The cancellation of stage 19 hands an advantage to Briton Mark Cavendish in the race for the red points jersey.

Cavendish, who struggles in the mountains, leads Evans by four points and Nibali by 10 in that particular race, but he was expected to lose the jersey on stage 19 with 25 points on offer for the winner, 20 for second, 16 for third and so on down to a point for the 15th-placed rider.

Now, even if Nibali, who wears the pink jersey as race leader, or Evans do pick up enough points to take the red jersey on Saturday, Cavendish could win it back if he were to triumph in Brescia on Sunday, where a sprint finish is expected.

The Manxman is looking to become just the fifth rider to win the points jersey on all three Grand Tours, having won the Tour de France and Vuelta a Espana equivalents.

Cavendish, who has won four stages of this year's Giro, tweeted: external-link "I remember waking up excited to see snow. Then I became a cyclist. Now I wake up to snow and have to wait to see if I'm excited or not."

It is the first stage to be cancelled since stage 18 of the 2001 Giro, although that was called off after police and custom officials raided hotels where the riders were staying in an effort to find drugs - in protest at their treatment, the riders refused to race.

The last stage to be cancelled due to poor weather conditions was during the 1989 edition.