* Spreadbetters see lacklustre opens for European bourses
* Crude futures tumble as Iran nuclear talks eyed
* Wall Street rallies on conditional Greek bailout deal
By Lisa Twaronite
TOKYO, July 14 (Reuters) - Asian shares turned lower and the euro slipped on Tuesday after the initial relief on Greece's conditional bailout agreement gave way to caution, as investors waited to see if the Greek parliament would accept harsh austerity measures as part of the deal.
Oil prices also skidded as the market awaited an announcement on a nuclear deal between Iran and six global powers that could lead to an easing of sanctions against Tehran and a resumption of its oil exports into an oversupplied market.
They will hold a full ministerial meeting at 0830 GMT, followed by a press conference.
Financial spreadbetters expected Britain's FTSE 100 and France's CAC 40 to open little changed, and Germany's DAX was seen up 0.1 percent.
"Markets had a solid rebound yesterday on the news that a conditional deal was on the table," Jonathan Sudaria, a dealer at Capital Spreads, said in a note.
"However, the need to pass even harsher measures through the Greek parliament could be another stumbling block and so we see markets treading water until we get some clarity," he said.
MSCI's broadest index of Asia-Pacific shares outside Japan was down about 0.1 percent, erasing earlier gains as Chinese shares slumped.
Shanghai's benchmark composite index was down 1.6 percent, while the CSI300 index of the largest listed companies in Shanghai and Shenzhen slipped 2.2 percent.
China stocks had risen for the past three sessions, which raised investors' hopes that Beijing's recent stabilization steps had worked to stem a massive correction.
Japan's Nikkei stock index outperformed, ending up 1.5 percent.
Later on Tuesday, Greece's Prime Minister Alexis Tsipras will face a showdown with members of his own party over the bailout agreement, under which Greece can get a possible 86 billion euros ($95 billion) over three years if it can satisfy its European partners that it is meeting their conditions.
The terms imposed by Athens' international lenders led by Germany obliged Tsipras to abandon his pledge to end austerity.
U.S. stock futures were flat, with S&P 500 mini futures down a few ticks from late U.S. levels, after Wall Street jumped on hopes for the Greece deal. All three major stock indexes ended up more than 1 percent, in what some strategists described as a relief rally.
But some said doubts would remain until the proposal is actually accepted.
"Investors did not like that a Grexit is still on the table if Parliament votes no," managing director at BK Asset Management, said in a note to clients. "The risk is far less now than a week ago but the fact that it is not eliminated puts pressure on the euro."
The euro last traded at $1.0990, down about 0.1 percent on the day. Against the yen, it slipped 0.2 percent to 135.53 yen.
The greenback was buying 123.32 yen, down about 0.1 percent on the day ahead of congressional testimony by Federal Reserve Chair Janet Yellen on Wednesday that will be closely monitored for any further hints regarding the timing of an interest rate hike.
"The dollar should have a relatively easy time topping 124 yen, especially if Yellen sounds hawkish during the testimony," said Junichi Ishikawa, market analyst at IG Securities in Tokyo.
In commodities trading, U.S. crude slipped about 1.3 percent to $51.50 a barrel, coming under renewed pressure as Iran appeared to be close to a deal with six world powers that would allow it to sell its oil again on the oversupplied world market.
Brent crude dropped about 0.9 percent to $57.32.
A draft nuclear deal between Iran and six major powers calls for U.N. inspectors to have access to all suspect Iranian sites, including military, based on consultations between the powers and Tehran, a diplomatic source said on Tuesday. (Additional reporting by Shinichi Saoshiro in Tokyo; Editing by Shri Navaratnam)