* Union says all sacked workers to be reinstated
* Proposal to return to work to be made to workforce Monday
(updates with union quote para 6 & 7)
LONDON, June 26 (Reuters) - A dispute involving hundreds of workers who were sacked last week for going on unofficial strike at a French-owned oil refinery in eastern England has been settled, interested parties said on Friday.
French oil firm Total said the dispute with some 650 construction workers at the Lindsey refinery, who were sacked for taking the unofficial industrial action, had put major investment into the building of its HDS-3 desulphurisation unit at risk.
But the dispute was settled late on Thursday after talks between unions and employers.
"Total is pleased that the contract companies and the unions were able to reach a positive conclusion at the talks tonight," a Total spokesman said early on Friday.
"We expect this means that the contractors will be able to get back to work as soon as possible and get the project completed on time with no further disruption and additional costs."
Unite, the main union at Lindsey oil refinery, later said employers had agreed to reinstate all the sacked workers.
"The proposals for a return to work will be recommended to the workforce by the union's shop stewards at Lindsey on Monday morning," its assistant general secretary Les Bayliss said in a statement.
Unions had been demanding the immediate reinstatement of the sacked workers as well as jobs for the 51 employees laid off at the refinery earlier this month.
Total had said on Tuesday that although production had not been affected at the refinery, which produces about 223,000 barrels of crude oil per day, delays and stoppages on construction had cost it 100 million euros ($138.6 million).
The row has also triggered widespread sympathy walkouts involving thousands of contract workers at power plants, refineries and gas terminals across Britain, unions say, though energy supplies have not been affected. (Reporting by Michael Holden; editing by James Jukwey)