Six people were killed by a bicycle bomb which hit shoppers at a crowded Afghan bazaar Friday as the government hit out at Pakistan over cross-border strikes following the death of four children. Five civilians plus one policeman died in the blast in the northern province of Kunduz while 22 others, including women and children, were wounded on Afghanistan\'s main weekly day of rest. \"Six people have been killed and 22 others injured as a result of today\'s explosion,\" provincial police spokesman Sarwar Hussaini said. \"There is one policeman among the dead, there are also three children, four women and one policeman among the injured. It was a busy bazaar. The Taliban are responsible, they want to terrorise people.\" The Taliban were not immediately contactable but frequently target the Afghan police and other government employees in their near decade-long insurgency. Civilians are the biggest casualties in the war with 2,777 killed last year, according to the UN. The north of Afghanistan is traditionally more stable than the troubled south and east but has seen an upsurge of violence in recent times. Earlier, the Afghan foreign ministry issued an angry statement urging an end to cross-border attacks from Pakistan, warning such incidents could affect \"improving trust and cooperation\" between the militant-plagued neighbours. It said four children were killed late Thursday by Pakistani shelling in the northeastern province of Kunar, the latest in days of claim and counter-claim by the two countries. \"The ministry of foreign affairs of Afghanistan expresses its serious concern about the continuing Pakistani artillery shelling of Afghan villages in Kunar and Nangarhar provinces,\" the ministry said in a statement. \"The Afghan government calls for the immediate cessation of the artillery fire against Afghan villages. \"The continuation of such incidents could adversely affect the spirit of improving trust and cooperation between the Islamic Republic of Afghanistan and the Islamic Republic of Pakistan.\" There was no immediate comment from Pakistan, where foreign ministry officials were wrapping up a fresh round of peace talks with India. Relations between Afghanistan and Pakistan are strained over the Islamist militancy faced by both which Kabul says is rooted in Pakistan. The border between Afghanistan and Pakistan is porous and Taliban and other militants make use of rear bases in Pakistan to launch attacks on government and foreign targets in Afghanistan. The issue of cross-border attacks is highly sensitive and has flared up with particular intensity in recent days. Last week, Pakistani officials said five people were killed when several hundred militants crossed from Afghanistan and targeted civilians in the Mamoond area of the lawless border tribal district of Bajaur. But Afghan officials denied any attack and accused Pakistani troops of killing six people in a rocket strike in Kunar, as well as other attacks in Kunar and Nangarhar. The statement came after Afghan Foreign Minister Zalmai Rassoul met the Pakistani ambassador to Kabul over the issue Monday. Pakistan had earlier summoned the Afghan charge d\'affaires. It was issued shortly before Afghan President Hamid Karzai was due to meet Pakistani President Asif Ali Zardari and Iranian leaders at a trilateral meeting in Tehran. The meeting will discuss issues including efforts against terrorism, a statement from Karzai\'s office said. Elsewhere in Afghanistan Friday, a foreign forces helicopter made a \"hard landing\" in the troubled southern province of Helmand but its crew members escaped unhurt, the military said, without giving further details.