KABUL — A suicide bomber detonated his explosives at the entrance to an American base in eastern Afghanistan today, killing three Afghan soldiers and one Afghan civilian, an American official said.

Initial reports indicated the bomber walked up to the first security gate outside of Forward Operating Base Bermel in Paktika province, an American spokeswoman, Major Christine Nelson-Chung, said.

She said three Afghan soldiers and one civilian were killed and that four Afghans were wounded.

No Americans were wounded in the attack, she said. It wasn’t immediately clear if the bomber had been trying to gain entry to the base, which is near the border with Pakistan.

Taliban insurgents have set off more than 100 suicide blasts this year, a record pace, and violence in 2007 has been the deadliest since the 2001 American-led invasion. More than 5,200 people have died because of the insurgency this year, according to an Associated Press count based on figures from Afghan and Western officials.

Australia’s prime minister, meanwhile, said more NATO powers must directly engage the Taliban to help ease the burden on Australia, American, Britain, Canada, and the Netherlands, which all have troops in the dangerous southern and central parts of Afghanistan.

Germany, Italy, France, and Spain have troops in the safer northern sections, and Prime Minister Howard said those countries need to help ease the burden on the countries in the south.

“Some of the other countries have lots of troops in Afghanistan but they’re not in some of the areas that are experiencing the heaviest fighting,” he said.

The governments of the Netherlands and Canada in particular are coming under domestic pressure to pull out troops because of heavy casualties.

“I think the Dutch government has been very courageous to date,” he said. “It’s not for me to comment on Dutch politics but I do observe that the Dutch are making a great contribution and as are of course the Canadians.”