* Questions over Greek buyback keep investors cautious
* Technical charts hint at rise to Bund range high
* Spanish bond yield edge up as ICO issue seen faltering
LONDON, Nov 30 (Reuters) - German Bund futures held firm within sight of recent highs on Friday as a turbulent week of trading ended with investors cautious over the implementation of a deal to release aid funds to Greece.
The deal, agreed earlier this week between euro zone finance ministers and the International Monetary Fund, had dented the appeal of Bunds. But doubts about the plan quickly surfaced and highly liquid German debt, to which investors turn in time of stress, recovered losses.
The Bund futures contract was last seven ticks higher on the day at 142.91, closer to the Nov. 13 high of 143.48 than the bottom of the recent range marked on Tuesday at 141.84.
"This reflects the fact that to a certain degree the market is not convinced about that deal," said Christian Lenk, fixed income analyst at DZ Bank in Frankfurt.
Questions centred on the proposal to buy back a portion of Greek debt, with investors on edge over a lack of clarity about how the operation will be funded and how repurchase prices will be decided.
"Uncertainty around eventual take-up at this reverse operation and the prospect of 'holdouts' again complicating the picture risk another unwelcome flare-up in market tensions," Lloyds Bank strategists said in a note to clients.
"This backdrop should prove sufficient to attract funds back into core product at higher yield levels, thus effectively providing a near-term cap to core fixed income rates."
Technical charts showed support for Bund futures at 142.62, the mid-point of Tuesday's steep sell-off, and a shift in momentum indicators towards fresh rises.
"As long as 142.62 is support we're happy bulls and expecting an assault on 143.48," said Futurestechs technical analyst Clive Lambert.
YIELD HUNT PAUSES
The subdued trading session brought a halt to the week's strong rally in peripheral debt, which briefly pushed Italian 10-year yields to a two-year low on Thursday.
Italian 10-year bond yields were steady on the day at 4.55 percent and Spanish equivalents rose 6 basis points to 5.42 percent, unwinding a portion of the 70 basis point rally seen since mid-November.
Traders said the new-found confidence in Spain had taken a knock with sources familiar with a bond issue from state-controlled credit agency ICO saying investors were not rushing to buy.
"Maybe it's because it's month-end and people are busy elsewhere but this ICO issue seems to be going a bit slowly and that's weighing on the sovereign market," a trader said.
A second trader said the peripheral rally may have run its course for the near term due to the looming risk that the U.S. economy could slip into recession if lawmakers fail to avert $600 billion of automatic spending cuts and tax hikes.
The U.S. "fiscal cliff" problem, along with concerns over the health of Spain's economy, were likely to keep euro zone markets in their current unusual state -- where both low-risk and high-risk assets are in high demand.
"Everybody is a little bit split. You want to be in the rally in the periphery but on the other hand you don't want to get completely out of your safe haven," Lenk said.