The Observer reports that the government has seriously underestimated construction costs for the 2012 Games. Plus, all the other news from the weekend papers.

This weekend’s papers reveal that the cost of staging the Olympics is set to double. The Observer reports that senior officials organising the games claim construction costs have been seriously underestimated by Tessa Jowell and the Department of Culture, Media and Sport. The paper reports that the government has appointed consultancy KPMG to begin a reappraisal of its Olympics costs.

The Sunday Times reports that a government-backed blueprint for “sustainable surburbia”, in which developers must conform to an extensive system of green measures including street-corner renewable power generators and features to encourage biodiversity, will be unveiled at this week's Thames Gateway. The paper reports that the ODPM has backed the plans, which have been drawn up by Essex council, and is pushing for it to be adopted by other local authorities.

In business news:

Saturday's Times reports that Gerald Ronson's Heron International is reconsidering the fate of its 23.3% stake in Crest Nicholson. The paper claims that Ronson is tipped to either sell or re-bid next month.

The Observer reports that housebuilders Persimmon and Westbury were in continued talks this weekend aimed at finalizing an agreed takeover, which could be announced by the middle of the week.

And finally:

More disgruntled politicians as Saturday’s Times reports that MPs have attacked the design of a £422,000 awning being erected in a House of Commons courtyard to shield them from the rain. The structure, which consists of 14 steel girders topped by a glass roof, has been approved by English Heritage but MPs say it is grotesque and a waste of money. Fifteen MPs have signed a Commons motion complaining that the structure is a hazard to tall colleagues, such as 6ft 8in Shrewsbury and Atcham MP Daneil Kawczynski.