An Israeli court has extended the detention of two pro-Palestinian activists taken from a flotilla carrying aid for Gaza last Thursday, according to a rights group representing them.

Adalah said the court in Ashkelon gave police an additional six days to question Spanish national Saif Abu Keshek and Brazilian national Thiago Ávila.

They were among about 175 activists detained when Israeli forces intercepted 22 boats in international waters near Greece. The others were later released on the island of Crete.

Israel has said Abu Keshek is suspected of affiliation with a terrorist group and Ávila of illegal activity. Spain and Brazil have said their detention is illegal and demanded their release.

Both men have been on hunger strike for the past six days, according to Adalah.