The organising committee for next year's football world cup in Brazil is coming under increased pressure to come up with a 'plan B' for some of the intended tournament venues.

A number of stadium construction projects are badly behind schedule and the flagship project - Arena Corinthians in Sao Paolo, due to host the first game of the World Cup - suffered a tragic blow on Wednesday (27 November) when a large crane collapsed and crashed through the structure. Two construction workers were killed and a number of others were injured in the incident.

Arena Corinthians now joins a long list of Brazil 2014 venues that have been severely delayed due to a spate of building problems, public protests and staff strikes due to complaints over working conditions.

In 2011, around 1,500 construction staff working on the redevelopment of the Maracana stadium went on strike following an on-site explosion, which left one worker seriously injured.

The Vivaldao stadium in Manaus and the Arena Pantanal in Cuiaba are believed to be the worst affected by delays, with the most optimistic predictions seeing the latter being fully operational "sometime in March or April".

World governing body FIFA had previously set a "strict deadline" of 31 December for all 12 World Cup stadiums to be completed - a feat that the organising committee admits is now simply unachievable.

For venues to adhere to FIFA's World Cup guidelines, a number of test events need to be organised and undertaken to try out access controls, safety and evacuation procedures.

A 'plan B' to solve the issues could see already scheduled games being rescheduled to other stadiums - and some venues being taken off the list of World Cup stadiums completely.

There are murmurs among FIFA executives that the difficulties in getting the stadiums ready in time are, at least in part, self-inflicted.

FIFA guidelines are that a minimum of eight stadiums are needed to host a World Cup, but the Brazilian organisers decided to go with 12 due to the interest and demand from across the country to get involved in the tournament.

The first game of the World Cup, at the Arena Corinthians, is scheduled to take place on 12 June with the final being played at the Estadio Maracana in Rio de Janeiro on 13 July.