* Existing Toll Collect contract runs out in 2015
* Expiry could open door to new investors
* Arbitration suit to continue in late September - source
* No comment from Allianz, Siemens (Adds Daimler, Deutsche Telekom reaction, source on arbitration)
FRANKFURT, July 15 (Reuters) - Germany's Siemens AG and Allianz SE may be interested in taking stakes in highway toll company Toll Collect, the German business daily Handelsblatt reported on Monday, citing company sources.
The paper said Toll Collect would offer Allianz much-needed returns in a low-interest environment, while helping Siemens expand its footprint in the European toll road market.
Munich-based Siemens is already involved in a new French toll collection system, for which it supplies onboard units for vehicles as well as the electronic detection equipment.
Siemens and Allianz both declined to comment on the report.
Toll Collect, the world's first satellite-based truck toll system, is 45 percent-owned by German carmaker Daimler AG , 45 percent by Deutsche Telekom AG and 10 percent by Vinci unit Cofiroute.
Their contract to run the toll system runs out in 2015, which could open the door to new investors, especially if a long-running legal dispute between the companies and the German government is resolved soon.
The government has been demanding about 5 billion euros ($6.5 billion) from the Toll Collect consortium to recoup lost revenue and penalties related to a two-year delay to the start of the system.
A government source told Reuters that arbitration proceedings are set to continue in late September, right after Germany holds its next federal election.
When the consortium's contract runs out in 2015, the government has three options for the toll system, two people familiar with the matter said.
It can extend the contract with the consortium, it can take over Toll Collect via a call option and then find new investors, or it can issue a new call for tenders, they said. The latter is the least likely option as time may not allow for a new tender.
A spokesman for Deutsche Telekom said the company had repeatedly said it was in principle interested in continuing the toll system but declined to comment further. Daimler declined to comment.
($1 = 0.7661 euros) (Reporting by Maria Sheahan; Additional reporting by Peter Maushagen, Andreas Cremer and Markus Wacket; Editing by Mark Heinrich)