BEIRUT (Reuters) - Lebanese security forces carried out a series of arrests overnight, security sources said on Friday, as part of a crackdown launched after twin suicide bomb attacks killed 44 people in Beirut last week.

Islamic State claimed the attacks, which targeted a busy residential and commercial suburb of the capital dominated by Shi'ite movement Hezbollah.

It was the latest spillover of violence from the Syrian civil war across the border, as Hezbollah steps up its involvement in the conflict in support of President Bashar al-Assad, fighting against insurgents that include Sunni Islamist groups.

The latest raids in Beirut and northern city Tripoli dismantled "networks that were planning to carry out a series of similar operations (to those in Beirut), in more than one location," a security source said on condition of anonymity.

Another security source said that 16 people had so far been arrested in connection with the Beirut attacks on November 12.

They include five Syrians, one Palestinian and one Lebanese man linked to the bombings, whose detention was reported on Saturday.

Security forces also arrested three people who were carrying explosives at a Palestinian refugee camp in southern Lebanon on Thursday, and earlier in the week the Internal Security Force said it had seized 180 kilograms of explosives in Tripoli.