The Senate subcommittee on international finance must decide within two weeks whether to allow the Export-Import Bank to continue financing a controversial and costly hydoelectric project in Zaire, despite two cost overruns and questions about Zaire's political and economic stability.

The project up for review is an 1,100-mile-long power line to transfer electricity from the Zaire Rive to the mineral-rich Shaba province in the southeast. The project was started in 1973 at an initial cost estimate of $341.1 million and is now 80 percent completed. But the latest price tag is $680 million, and Ex-Im Bank now needs $93 million to keep the project alive.

Congress' decision on the project will be the only official vote of confidence on how well Zaire and its president, Mobutu Sese Seko, have progressed in improving relations with Angola, curbing its own corruption and improving its human rights record.

Also at issue is simply whether Zaire is able to pay its bills.

By law, Congress has 25 days after the initial request for more money to veto any further Ex-Im Bank loan extensions to Zaire. The Senate subcommittee, in considering the project, is weighing a resolution that would stock any further Ex-Im loans to Zaire until Mobuto agrees to an economic stabilization program, and is able to guarantee repayment in full.

WaNsanga Mukendi, a visiting associate professor from Amherst College and a Zaire native, told the subcommittee this week that he objects to the project on grounds that it would "only intensify Zaire's already heavy dependence on a mining-based economy." The project is designed essentially to provide electricity to the Shaba copper mining interests to accommodate expected increases in Zaire's copper and cobalt production.

Ex-Im Bank officials testified that the reason for the massive cost overruns and repeated delays was "lack of steady local funding from the Zaire government." Also, the mid-May 1978 invasion of Shaba by Angola-based rebels set the project behind schedule as well as scaring off many workers employed by the power line builders.

Reports of Mobutu's corruption also fueled senatorial resistance to further financing of the project. "When you see this kind of money being sent to a country that has a history of corruption, you hesitate," Sen. Paul Tsongas (D-Mass.) said.

John Lange, Treasury Department Director of trade finance, conceded that "this is not a good project for the government." He added: "Having gone this far with the project, I can't see anything else we can do but complete this project."