NEW YORK (Reuters) - IBM reported a better-than-expected 24 percent rise in preliminary quarterly earnings yesterday on strong sales in overseas markets, driving its shares up six percent and spurring a broader tech rally.

The surprise report ahead of International Business Machines Corp's scheduled earnings release on Thursday eased some concerns over how much the slowing US economy has hurt the world's largest technology services company.

IBM said six percentage points of its 10 percent revenue increase were due to currency benefits as the dollar weakened.

"We think IBM saw fundamental upside from most of its operating segments, though much of the December quarter upside was driven by the strength of its international end-markets," Goldman Sachs analysts said in an investor note.

The report boosted US stocks across the board following a dismal start to the year, with IBM leading gains on the Dow Jones Industrial Average and pushing the Nasdaq higher.

Investors have retrenched on concerns the US may be heading into a recession amid a worsening housing and credit crisis.

Technology, seen late last year as a safe haven as investors fled housing, financial and consumer discretionary stocks, had been the worst-performing sector on the Standard & Poor's 500 index, down nearly 10 percent through Friday.

Asked why IBM reported fourth-quarter results four days before the scheduled announcement, a spokesman said: "Given the economic climate in which there's been a good deal of speculation about market conditions and the performance of technology companies, IBM wanted to deliver this information to investors."

But despite the report concerns remained on Wall Street about the strength of demand from US companies.

Jyske Bank analyst Robert Jakobsen said some companies may have inflated their tech spending in the last quarter to protect their 2008 budgets in case of a slowdown.

"We just need to see the guidance for the first quarter or 2008," he said.

IBM said fourth-quarter earnings from continuing operations rose to $2.80 a share from $2.26 a share a year ago. That beat by 20 cents the average Wall Street forecast for earnings of $2.60 per share, according to Reuters Estimates.

Revenue in the fourth quarter rose 10 percent to $28.9 billion, also beating the average analyst estimate of $27.8 billion.

IBM gave no outlook beyond a quote from chief executive Samuel Palmisano that it was "on track to achieve our long-term earnings-per-share road map objective in 2010".

IBM, based in Armonk, New York, had forecast earnings per share would grow to about $11 in 2010 from $6.06 in 2006 as it boosts revenue and profit margins, buys back shares, invests in its business and makes acquisitions. Yesterday's preliminary report pushed IBM shares as high as $105.59 in early trading on the New York Stock Exchange, before they settled at around $103.68, up six percent in the afternoon.

IBM stock had fallen 18 percent since its last earnings report on October 16, when it said third-quarter revenue growth was held back by weakness among US financial services clients.

Yesterday's announcement also spurred gains in the Dow Jones industrial average and Nasdaq, with other tech shares such as Intel Corp, which is due to report results today, and Hewlett-Packard Co rising about three percent.

Peter Misek, an analyst at Canaccord Adams, said the fact IBM only referred to overseas markets bode well for other internationally focused companies.

"Our view is this is very positive for the likes of Intel and Microsoft and any other large multinational that gets a large proportion of its revenue overseas," he said.

Microsoft Corp. shares were up about one percent.

Tim Ghriskey, chief investment officer of Solaris Asset Management, which has about $2 billion in investments and does not own IBM shares noted that, while US weakness did not appear to a problem abroad, that could change quickly.

"We are seeing some weakness in housing in Europe and weak housing is what has hurt the US economy, so we could see the same thing beginning to unfold in Europe over the coming months," he added.