Both sides reported heavy fighting as Taliban militants attacked government positions in Sangin district, an area where insurgents have made major gains in the past two years.
"There is heavy fighting still ongoing between the Taliban and our forces but those places that were captured by the Taliban yesterday have been taken back," said Omar Zwak, a spokesman for the governor of the southern province.
Among the reinforcements sent to the embattled district were new commando units, he said, Reuters reported.
A regional Taliban spokesman, Qari Yousuf Ahmadi, said fighters had captured at least 25 government checkpoints and killed more than 100 soldiers and police.
The Taliban used tunnels dug from houses to attack the government's front-line checkpoints, General Wali Mohammad Ahmadzai, commander of the 215th Army Corps, said on Monday.
Army officials said they had killed at least 19 Taliban and wounded 25.
British, American and other international forces battled the Taliban in Helmand for years after the ouster of the militant group from power in late 2001. Sangin and other districts saw sustained heavy fighting.