The taps feeding a pipeline carrying oil from landlocked Niger to Benin for export have been shut off, Nigerien public television said, escalating a diplomatic row between the neighbours.

Ties have been strained since last year's coup in Niger, and the Benin port of Seme-Kpodji, which exports Niger's oil, has emerged as a flashpoint.

Under regional sanctions imposed on Niger after the coup, Benin closed the border but has since reopened it. Niger's military rulers, however, have refused to reopen their side.

Benin also announced on national television last week that it was lifting a "blockade" on Nigerien oil.

But Nigerien public broadcaster Tele Sahel reported Thursday that Oil Minister Mahamane Moustapha Barke was in the country's east earlier this week to ensure "the implementation of the instructions of the head of state, General Abdourahamane Tiani, relating to the total closure of the valves of crude oil destined for export" via Benin.

One station's valves had already been closed since June 6, the broadcaster said, while others where the oil was still flowing were ordered shut by the minister, with chains and padlocks installed.

"Whatever it will cost us, we are ready to bear it," Barke told Nigerien officials and Chinese partners in the stations.

The oil is essential to the economies of both countries, and to the Chinese company Wapco, which operates the pipeline.

Last week, five Nigeriens were arrested at the Seme-Kpodji port, with authorities in Benin accusing at least two of them of being "agents" of the Nigerien junta posing as Wapco employees.

Niger denies the accusations.

Barke said last week that General Tiani had given orders to shut down one pumping station if the five weren't released.