KABUL - Taliban insurgents will redouble their efforts to disrupt presidential elections in Afghanistan next month after failing to sabotage the first round of voting in April, a senior US general said Saturday.

"I think the enemy is going to make a push on run-off day," said Major General Stephen Townsend, commander of NATO-led forces in eastern Afghanistan.

The first round of voting on April 5 went ahead without major violence and with a significant turnout, despite efforts by Taliban and affiliated militants to sabotage the election, Townsend told AFP in an interview.

Afghan army and police are now leading the fight against the Taliban as international troops withdraw from the country in December after more than a decade of war.

For the April 5 polls, US and coalition troops mostly stayed on their bases and kept a low-profile, leaving it to Afghan forces to oversee security while providing intelligence and logistical support.

If the insurgents manage to disrupt the run-off vote in June, that could "erase" the success of the April 5 election, Townsend said.

Townsend oversees more than 9,000 ISAF forces in some of the most volatile areas in the country where Islamist extremists, including the Haqqani network, remain entrenched in the east and southeast.

The Haqqani network, blamed for numerous deadly attacks against US and NATO forces, has shown some signs of disarray in recent months, he said.

"Their funding stream seems to have declined a bit. There's competition in the world for fighters and funding, there are other shows in town," he said.

However, the network still poses a genuine threat and is intent on orchestrating high-profile attacks in Kabul and elsewhere, he said.

About 100 to 150 "hardcore" members of the terror network are based in the area and are kept in check by relentless pressure from coalition forces, he said.

"Strategically they're not effective. They're not plotting and planning and conducting international, transnational operations," he said.

"What they're doing up there is they're existing, they're surviving."

He said there was a "constant operation" aimed at the Al-Qaeda extremists led mainly by special operations forces, which focuses "exclusively" on them and "those that support them". (AFP)