(CNN) -- Afghanistan's ruling Taliban militia claimed that Iranian jets and helicopters violated Afghan airspace Friday and vowed again to retaliate if Iran attacks its territory.

Iran has massed 270,000 troops along its border with Afghanistan and has been preparing for a full-scale military exercise that could begin as soon as Saturday. Iranian television Friday showed footage of aircraft and helicopters dropping bombs and firing rockets in what was described as preparations for war games.

But the Taliban's ambassador to Pakistan, Maulvi Saeed-ur-Rehman Haqqani, told the Pakistani news agency News Network International that 15 Iranian fighter jets and 15 helicopters made incursions into Afghanistan Friday.

Also, the Afghan Islamic Press quoted a Taliban official as saying that there were three incursions of Iranian jets in the skies above Nimroz province, which borders Iran, on Friday morning.

There has been no independent confirmation of any Iranian violations of Afghan airspace.

Tensions between Iran and the Taliban have been escalating since August, when eight Iranian diplomats and a journalist were slain in the Afghan town of Mazar-i-Sharif after it fell to the Taliban.

The Iranians also accuse the Taliban of persecuting Afghanistan's Shiite Muslim minority. The Taliban are adherents of the Sunni branch of Islam, while most Iranians are Shiites.

After the slayings, Iran announced that it would conduct a massive military exercise, called Zolfaqar-2, near the Afghan border. Defense Minister Ali Shamkhani said last Saturday that the exercises would begin within a week.

The Taliban are believed to have deployed 10,000 soldiers at the border. Earlier this week, 4,000 fresh troops were reportedly sent into the border region.

While saying the Taliban would not initiate a war with Iran, Haqqani said the militia would strike back if Iran attacks.

Reuters contributed to this report.