* FTSEurofirst 300 up 0.5 pct
* UBS sees positive revenue trends
* Ongoing caution over Greece hinders euro zone
* Britain shares outperform; calm ahead of election
By Alistair Smout
GLASGOW, May 5 (Reuters) - Shares of Swiss bank UBS were the top performers in Europe on Tuesday, rising on the back of its highest quarterly profit in nearly five years, as gains for non-euro zone shares helped European stocks into positive territory.
The pan-European FTSEurofirst 300 index was up 0.5 percent at 0756 GMT, though euro zone indexes in Germany, Italy and Spain were flat to 0.2 percent lower.
The broader market was lifted by UBS' results. The bank rose 4.4 percent, with some analysts pointing to positive revenue trends and encouraging development in wealth management.
Switzerland's SMI was up 0.1 percent, with UBS the top riser on the index.
"The numbers looked good across the board. The revenues were strong and the fund management division performed well," said Clairinvest fund manager Ion-Marc Valahu.
The broader FTSEurofirst 300 was also lifted by a 0.5 percent rise for Britain's FTSE 100, catching up after the London market was shut for a public holiday on Monday.
European shares had advanced in thin trade on Monday, boosted by better-than-expected German manufacturing data and merger and acquisition speculation about chemicals companies.
However, Germany's DAX fell 0.2 percent on Tuesday after gaining 1.4 percent in the previous session. Allianz was a top faller, down 1 percent after the insurer was downgraded to underweight from equal weight by Barclays.
Euro zone shares were also under pressure from continuing uncertainty over Greece, traders said.
Wide differences over pension and labour reforms continued to dog intensive negotiations between Greece's leftist government and its international creditors despite progress in other areas as the country's cash position becomes increasingly critical.
Greece's ATG share index was down 2.4 percent.
"We really do think time is running out over Greece. Everything has pointed to this being the week in which a deal needs to be done," Jeremy Batstone-Carr, market analyst at Charles Stanley, said.
"Greece is having huge difficulties making payments to the IMF, and the IMF is in no mood to soften its stance."
Some investors fretted over the potential of further political uncertainty from this week's British general election, as the cost of protection against big swings in sterling in the next week spiked to its highest since the previous vote in 2010.
However, just two days before Britons vote in the closest-fought electoral race in recent history, stock markets remained calm, with volatility on the FTSE 100, a crude measure of investor concern, dropping 3.5 percent
Europe bourses in 2015: link.reuters.com/pap87v
Asset performance in 2015: link.reuters.com/gap87v
Today's European research round-up
Additional reporting by Sudip Kar-Gupta