* Soldier first to be killed along border since uprising
* Jordan security say al Qaeda threat growing inside kingdom (Adds details and background)
AMMAN, Oct 22 (Reuters) - A Jordanian soldier was killed in clashes with Islamist fighters trying to cross the country's northern border into Syria, a cabinet minister said on Monday.
"The soldier died during an infiltration attempt," Minister of Information Samih Maaytah told Reuters, adding that it was the first death in Jordanian army ranks on the border since the uprising against Syrian President Bashar al-Assad broke out in March last year.
Troops detained 12 Islamist fighters after the clashes, which occurred overnight, an army statement said.
Jordanian authorities have privately expressed concern about the growing threat of Islamist jihadists infiltrating into Syria to join scores of radical groups operating across the country.
Jordan said on Sunday it foiled a plot by an al Qaeda-linked cell to bomb shopping centres and assassinate Western diplomats. Security sources said the 11 suspects detained, all Jordanians, had envisaged carrying out attacks in the capital Amman using smuggled weapons and explosives from Syria.
Security sources said the suspects had spent some time in Syria, without saying when they had returned to Jordan.
A key U.S. ally in the Middle East and Israel's peace partner, Jordan enjoys close ties with Western intelligence agencies and has often been targeted by al Qaeda and other Islamist militants. (Reporting by Suleiman Al-Khalidi; Editing by Dominic Evans)