The Palestinian Fatah faction has accused the ruling Hamas movement of plotting to kill Palestinian leader Mahmoud Abbas and other officials.
Tensions between Fatah and Hamas have soared in recent months
A Fatah spokesman said tunnels laden with explosives believed to be aimed at senior Fatah members have been unearthed in Gaza.
He said the party believes they were dug by the militant group Hamas.
The group dismissed the claims, saying the tunnels were intended to defend against Israeli incursions.
This comes amid an ongoing power struggle between the two rival factions in Gaza.
At least 30 people have been killed in fighting between Hamas and Fatah in Gaza in recent weeks.
Fatah spokesman Abdel Hakim Awad said about five tunnels had been discovered over the past few days.
Mr Awad said some of the tunnels started underneath mosques and one ran under the home of a senior Fatah man in the Jabaliya refugee camp.
Another was found underneath a road used by Fatah leader and Palestinian Authority President Mahmoud Abbas.
"Because of the gravity of this action, which we think represents malignant and premeditated intentions to assassinate leaders and symbols of Fatah and the authority, including President Abu Mazen [Mahmoud Abbas]... we in Fatah hold Hamas completely responsible for any such action," Mr Awad was quoted by the Associated Press news agency as saying.
Hamas dismissed the allegations, denying there was any conspiracy planned.
A Hamas spokesman suggested that Fatah was deliberately manoeuvring to further sour the atmosphere in Gaza.
The BBC's Alan Johnston in Gaza says although tensions between the two parties do remain acute, the violence on the streets has actually ebbed away almost completely over the past 10 days or so.
He says recent speeches by the most senior figures have been much more conciliatory, giving rise to hope that serious dialogue might be resumed.