The divisions and mistrust that have long plagued Syria's rebellion against President Bashar Assad erupted once more on Tuesday — this time over the flag.

The dispute was sparked by a press conference in Istanbul by the Syrian National Coalition, the main opposition group in exile, when its leader Khaled Khoja decided not to display the flag that for the past four years many have adopted as the symbol of their revolt against Assad — a green, white and black flag with three red stars in the center.

He did so at the request of Louay Hussein, an opposition figure who only recently left Syria into exile. Hussein argued that just displaying the flag would be divisive. He said either the official Syrian flag — which is red, white and black with two green stars in the center — should also be shown at the gathering or neither should. Many in the opposition consider the official flag to be the symbol of Assad's rule, a claim Hussein countered.

"It is not the flag of the regime. We shouldn't throw it to the regime," Hussein said during the conference Monday, standing next to Khoja.

Activists vented their outrage at Khoja for agreeing to the request and denounced Hussein.

"We find in it an unforgivable insult to the revolution," the Local Coordination Committees, an anti-Assad activist group, said in a statement. It compared Khoja's decision to the way Assad supporters tromp on the flag — or the way Islamic extremists tear it apart. Militants reject both flags, flying a black banner instead.

The press conference was held to announce that the National Coalition and Hussein's political party will not attend low-level consultations hosted by the U.N. envoy in Geneva in hopes of restarting peace talks.

But the flag controversy overshadowed the diplomacy.

The flag adopted by many in the opposition was first used by Syria when it became a republic during the French colonial mandate in 1930 and when the French left and full independence was gained in 1946. It was replaced by the current flag in 1958, when Syria was briefly unified with Egypt in the United Arab Republic.

The Local Coordination Committees said the "independence flag" represents "a new era of democracy, freedom and dignity" and a break with Assad's era. It added that it was used to wrap many of those killed in the civil war.

But just as Syria's civil war has taken on bitter sectarian overtones, so have the flags. Syria's rebels are largely from its Sunni Muslim majority. Assad is a member of the member of the Alawite religious minority, which strongly backs his rule as do other minorities, fearing a Sunni takeover. To them, the official flag is a symbol less of Assad's ruling Baath Party than of secular nationalism.

In a post on his Facebook page after the outrage, Hussein said he had proposed that both flags be raised at the conference to ensure the opposition is inclusive, even of allies who are "silent or afraid." But since no official flag was available in Istanbul, neither was put on display, he said.

"There was no intended denial or offense to any Syrian flag. But I am afraid there are some who want to obstruct any national act that aims to unite and save Syria from collapsing," he wrote.

The opposition Orient TV lashed out at Hussein, accusing him of being a latent regime supporter who, as an Alawite, incites sectarianism and is trying to co-opt the opposition. "He is (daring to) correct Khoja, correct even the revolution," the broadcaster said.

Khoja later tweeted that "the revolution flag" is a source of pride to him. "I look to the day that all forces and factions of the revolution adopt it."