* FTSE 100 rebounds after Putin speech
* Index moves above 200-day moving average
* Carnival lifted by UBS price target upgrade
LONDON, March 18 (Reuters) - Britain's top share index rose on Tuesday as stock markets rebounded after a speech by Russian President Vladimir Putin on Ukraine, which some traders interpreted as being conciliatory in tone.
The blue-chip FTSE 100 index was up 0.8 percent, or 50.52 points, at 6,618.87 points in late-session trading.
Cruise ship operator Carnival was the best-performing FTSE 100 stock in percentage terms, rising 3.5 percent to 2,464 pence after UBS raised its price target on the shares to 2,600 pence from 2,500 pence.
The FTSE had been in negative territory for much of the day but rallied after Putin said Russia did not want to seize more of Ukraine after approving plans to make Crimea part of Russia.
Putin also said that while Russia would look to defend its own interests, Russia would never seek to start a confrontation with Western powers.
"It's not quite as aggressive as some people had thought," said Mark Ward, head of execution trading at Sanlam Securities.
In spite of the FTSE's rebound, the index remains below its 2014 peak of 6,867.42 points reached in late January.
The FTSE rose 14.4 percent in 2013 to post its best annual gain since 2009.
Many traders expect the index to hit a record high of 7,000 points later in 2014 as Britain's economic recovery slowly gathers momentum, but the FTSE has failed to break above the 6,900 point level so far this year and is down by 2 percent since the start of 2014.
Some other technical traders saw support for the FTSE from the fact that the index's rebound had pushed it above its 200-day simple moving average - often used by such traders as a sign that a market's decline has run its course.
Adrian Slack, technical strategist at London-based firm APS Alpha, said that if the FTSE could hold above that 200-day average - which lies around 6,580 points - it could then push on to reach 6,750 points.
"I fancy the FTSE to push higher as long as it can hold above that 200-day moving average," he said.