UPDATE 1-Gunmen kidnap 16 Afghan demining workers-police

* Gunmen kidnap Afghans working for demining agency

* No claims of responsibility made (Adds Dutch aid agency staff kidnapped)

GARDEZ, Afghanistan, July 5 (Reuters) - Unidentified gunmen have kidnapped 16 Afghans working for a United Nations-sponsored demining agency in eastern Afghanistan, U.N. officials and police said on Sunday.

In a separate incident, two Afghan employees working for a Dutch aid agency were also abducted in a neighbouring province in the east on Saturday, the Afghan Health Ministry said.

The Afghan deminers work for the Mine Detection and Dog Centre (MDDC), part of the overall U.N. mine clearing agency in Afghanistan known as UNMACA. They were seized while travelling between Khost and Paktia provinces late on Saturday, Paktia's police chief said.

"We do not know who kidnapped them and why. We are investigating," Azizullah Wardak told reporters in the Paktia provincial capital Gardez.

UNMACA official Gul Agha Ahmadzai said they were snatched as they drove along the Logar-Gardez road which links with Khost.

Afghanistan is one of the most heavily mined countries in the world after almost 30 years of war, with more than 640 sq km (250 sq miles) of land still containing mines.

In neighbouring Khost province, two Afghans working for HealthNet TPO (HNI), a Dutch aid agency, were abducted on Saturday, health ministry spokesman Ahmad Farid Raaid said. He had no further details.