OTTAWA - Foreign Affairs Minister Lawrence Cannon says officials have been working in diplomatic channels and on the ground but apparently have no solid leads in their efforts to track down two Canadian diplomats who disappeared in Niger last month.

Cannon says "all resources" at the government's disposal -- including RCMP and military -- are being brought to bear in the search for UN special envoy Robert Fowler, his Canadian assistant Louis Guay and their driver.

The three disappeared after paying an unofficial visit to a Canadian-run gold mine about 125 kilometres from Niger's capital Niamey on Dec. 18.

No ransom demands have been received and authorities are looking at all hypotheses, Cannon said Wednesday.

A rebel group in Niger, Front des forces de redressement, posted conflicting statements on its website the day of the disappearances, first claiming responsibility for the apparent kidnappings, then denying it had anything to do with them.

The group said it does not take hostages and expressed hope Fowler and his associates would turn up soon.

It said authorities had received reports of a car registered in neighbouring Togo that allegedly followed the diplomats' vehicle from Niamey.

Fowler, 64, was a senior adviser to several prime ministers, including Pierre Trudeau, John Turner and Brian Mulroney, and served as an ambassador to the UN. He also played a leading role in thwarting the trade of so-called blood diamonds in Angola.

There is speculation Fowler may have been abducted as part of a complex conflict involving the government of Niger, rebel groups and international mining companies.

Mainly nomadic rebel groups want to overthrow the country's democratically elected government because they say mining companies are ravaging their traditional land, and they're not receiving fair royalties.