(Reuters) -British homebuilder Crest Nicholson said on Friday rival Bellway's revised and unsolicited 650 million pound ($828 million) all-share takeover offer "significantly undervalued" the group, sending shares up 8% in early trade.

Bellway on Thursday made public the new bid it had proposed on May 7, valuing Crest at 253 pence a share - a 30% premium to Crest's closing share price on the day of the bid.

An earlier offer was rejected in April, Crest said in a statement.

The latest bid, which would have valued Crest at about 650 million pounds ($829.53 million) according to a Reuters calculations, underscores consolidation efforts in the UK's homebuilding industry.

Earlier this year, Britain's biggest homebuilder Barratt agreed to buy Redrow in an all-stock deal, while Vistry bought Countryside in 2022.

A shortage of properties has been driving up the cost of owning a home in Britain and alienating many younger voters who, paying high rents, cannot see a way to own their own homes in the country where housing has long been a political issue.

The competition regulator had said builders and the government need to fix the shortage.

Bellway had said there was "compelling strategic and financial rationale" for a combination with Crest, with long-term opportunities to grow in the market.

Earlier on Thursday, Crest warned its annual profit would drop by at least a third and reported an 88% slump in half-year earnings.

Bellway on the other hand raised its annual average selling price forecast last week and pointed to strong trading in the spring selling season, as improved affordability from expected reductions in borrowing costs lifted customer confidence.

Crest shares were trading higher at 230.20 pence early on Friday, while Bellway stock was down 2.2% at 2,658 pence.

($1 = 0.7850 pounds)