March in Pakistani city was held by Jamaat-e-Islami political party to express solidarity with the people of Kashmir.
Dozens of people have been wounded after a grenade explosion at a pro-Kashmir march in the southern Pakistani city of Karachi, according to local officials.
Wednesday's attack in the Gulshan-i-Iqbal area targeted a rally organised by Jamaat-e-Islami (JI), one of Pakistan's major religious parties.
The provincial health department said in a statement at least 39 people were wounded, including one person who was in a critical condition.
An ethnic Sindhi armed separatist group, the Sindhudesh Revolutionary Army claimed responsibility for the attack in a statement emailed to Al Jazeera.
In June, four people were killed including two soldiers in three consecutive explosions claimed by the SRA.
The group wants Sindh province, of which Karachi is the capital, to break from the Pakistani federation.
It has also announced its alliance with the Balochistan Liberation Army, a rebel group fighting for greater autonomy for the Balochistan region in southwestern Pakistan.
Siraj ul Haq, JI chief and a senator, condemned the attack, calling it a "deplorable" act.
The JI rally was organised to express solidarity with the people of Indian-administered Kashmir on the first anniversary of India's controversial decision to revoke the state's semi-autonomous status.
On August 5, 2019, India's government revoked Kashmir's limited autonomy, promising that the move would facilitate economic development by bringing the territory into the country's administrative mainstream.
Since then, hundreds of thousands of Indian security forces have enforced a virtual siege in the territory, implementing widespread curfews and lockdowns, controlling citizens' movements, banning protests and cutting off the region's mobile internet connectivity.
In a speech marking the occasion on Wednesday, Pakistani Prime Minister Imran Khan reiterated a call for the world community to intervene in the Kashmir dispute by demanding Kashmiris' right to self-determination be implemented.
"Today, [Indian Prime Minister] Narendra Modi is exposed in the world," said Khan. "And the biggest thing to come from that is that the world is now looking at Kashmir."
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